White huns start off in Transcaspia, in a tricky position. You'll be facing the full might of the Sassanid BFF-empire to south. To the east there is nothing, literally. To the north you'll find the frozen wastes of Scythia and Hyperborea, home to poisonous slavs and nomadic hordes. To the west, the Caspian sea blocks off any immediate movement.

Luckily, the Hephthalite hordes have a wonderful arsenal at their disposal and some pretty useful faction traits. In addition, you can't settle. This is actually wonderful news. The creeping climate change means very little to you, and you can always relocate when a 10.000 strong eastern spam-stack threatens your 1000 man stack. It may be worthwhile to familiarize yourself with basic horde mechanics before reading further. To be brief: always try to end your turn with the horde encamped, unless you are raiding a trade route, or forced to flee as far as possible (which will happen at some point, make no mistake). Try to position your hordes so that rivalry is minimized - this means paying attention to the borders of provinces and regions, and placing your hordes on different sides of them.

Your faction traits give you +20 morale against easterners, immunity to desert attrition, and +100% income from sacking, looting and raiding. This should give you some idea as to what the game is trying to tell you to do. You'll be heading south to bring an (satisfying) end to the Sassanid empire.

Before we discuss the campaign strategy, it might be a good idea to look at the basic structure of a horde army. The following build is a personal preference, which I found to work for me. I'm sure you could make a pure horse archer build, or a more melee focused build work as well. This build should be able to take on 2:1 odds comfortably, and with skilled micromanagement even 3:1 is doable.

Your general will always be a decent melee cav unit. That said, keep him safe. Sassanids do like their spears.

Infantrywise, I go for 4 units of Xionite spears and 2 melee infantry. Xionite spears are decent for holding the line, and they have an amazing special ability which will melt away any cavalry that engages them. I ended up using this unit all the way to the end of the campaign. Yanda spearmasters are great too, but the Xionite spears get the job done cheaper + cavalry counter tactics is such an amazing ability that I just could not give it up. When it comes to melee infantry, you'll probably want to move on from steppe tribespeople to steppe warriors as fast as possible. After that, you'll be aiming for Khingilas khandas / Uar warriors. After that, Chosen Uar warriors. Guardians of the Hindu Kush are an amazing shock infantry unit but a bit too vulnerable to skirmishers and charges in my opinion to be 100% reliable.

Next, melee cav. This is where I started to experiment between hordes. For some hordes, I skipped melee cav completely - the reason for this will come clear later. For other hordes, I went with 2 units of melee cav. Early on, these units can be pretty much anything you want, they are all pretty crappy, until you can get the Hephthalite chargers. When you can train the Chargers, go for it. They will be your go-to melee cav for the rest of the campaign.

I wouldn't bother with shock cavalry. They require a bit too much micromanagement, and you'll have your hands full as it is. White huns can also get elephants in the late campaign. Again, I would advise against them. They are simply not cost effective, and die way too fast.

The rest of your army should be horse archers. At first you'll want the fastest units, which would be the Steppe mounted bows - Steppe horse archers. Later, when you can get speed upgrades through your generals, buildings, technologies etc,. and you can afford it, you should get Hunnic horse archers and Spet Xyon Archers (or purely Spet Xyon Archers).

So to sum up: your (full stack) army should look something like this:
1 general / 4 spears / 2 melee infantry / 2 melee cav / 10 horse archers/ 1 reserve slot
or
1 general / 4 spears / 2 melee infantry/ 12 horse archers / 1 reserve slot

Notice the reserve slot? this is where you can put whatever you need / want. If you want the Guardians of the Hindu Kush or the elephants, go for it! If you feel like you need onagers, by all means! If you feel like extra spears or melee inf. are required, do it! And having one more horse archer unit is always good too! It makes sense to have one unit which you can disband in order to make room for onagers, when attacking settlements. I tend to simply hire the onagers as mercenaries when I have to take a walled city. Just remember to disband them after the battle!

You'll want to get your three starter stacks to full strength as soon as possible. Before you can afford full stacks, though, one of your hordes will probably be undermanned. Just try to keep the same structure of a short(ish) spear line and a majority of horse archers.

As for tactics, mobility is the key for winning battles as the Hephthalites. What I do is find a defensible position for my infantry, melee cav and general, form a spear line, position my melee infantry behind the spears, general behind the melee infantry, and place the Hephthalite chargers on the flanks.

I divide my horse archers into two groups, set them to skirmish and rapidly advance on the enemy. Divide the groups so that one group attacks the right flank, and the other group the left flank. Depending on the strength of the enemy, it might be wise to turn off fire at will. If the enemy has a huge advantage in numbers, it is a good idea to pick your targets carefully and not shoot at just everything. If the enemy has cavalry, they tend to charge you as you approach. Turn on flaming ammo and simply burn them away as they try catch you. Once you get rid of the cavalry, try to kill off the general by positioning one group of horse archers behind the enemy's main line. They will no doubt try to maneuver in order to present you with their front. Just keep moving around them and try to pressure the general from several sides. If the enemy general proves too elusive, start to focus on heavy infantry (heavy shot can help here). Unless the enemy has a HUGE missile superiority I tend to ignore foot skirmishers, you can always mow them down in melee later, just don't get too close to javelins. When shooting at melee infantry, it is wise to focus fire on a single unit. Take out the biggest threats first. If the enemy has siege engines they quite often leave them unprotected when you start maneuvering around their main line. When you see a chance to get at the onagers, charge in! Don't waste your ammo on them, the siege engines can soak up a surprising amount of arrows.

If the enemy is attacking they should be moving towards your spear line which was stacked away safely behind, preferably on a hill. When the enemy approaches your spear line they should be considerably weakened by the constant skirmishing. When their remnants engage your spears, either push the melee infantry through your spears to where you think the biggest threat to your lines breaking is, or try to flank the enemy (standard hammer and anvil). If the enemy has any melee cav left they will try to flank your spears. This is where bringing Hephthalite chargers pays off. They have the same wonderful anti-cavalry ability that the Xionite spears have. Pop that, and remove the flanking cavalry. Your general can also stop a flanking attempt, if you have no melee cav in reserve. Once the enemy has committed his infantry on your line, you can charge in their rear with your horse archers, general and Hephthalite chargers, picking off any skirmishers and possibly taking out the enemy general on the way. This is where Spet Xyon archers shine! After having served their purpose as horse archers, they make a decent melee cav. While not the light tanks they used to be, they can still hold their own in a melee. Charging the rear of an already engaged infantry unit with pretty much any cavalry (even flimsy steppe horse archers) should set the enemy morale wavering and you'll probably start to see the first routs. Pretty soon you'll be mopping up the rest of the fleeing army.

If the enemy remains stationary, simply move your infantry lines and melee cav forward, trying to goad the enemy into engaging. Xionite spears have javelins, which might do the trick. On an aside note, remember to turn off fire at will from the steppe warriors when they are stationed behind your spears. Friendly fire is real. If you are forced to advance, try to take out the siege engines with a charge from the horse archers.

As for sieges, it is unlikely that you'll find yourself defending an ally city. If that happens, you can place horse archers on the walls, and block of any breaches with spears. Or charge out with the HA.

When attacking cities, prolonged sieges are a good option if you're not confident that you can take them out without staggering losses. Eventually the enemy will rally out, which is great news for you. Most of the time though, simply hiring a merc onager, punching a hole in the wall, skirmishing with the horse archers and charging in with the spears and melee infantry should see you winning the battle. Generally, avoid assaulting a city defended by A LOT of heavy spears. They can turn the streets in to deadly choke points, which you can't easily get around.

Try to keep a good balance of growth, integrity and income. If you have to sacrifice one of them, my advice is to cut back on integrity. You get bonus integrity from waging several concurrent wars, and from winning battles, anyways. Honestly, very few factions will like you, so you might as well start declaring wars left and right to keep up the integrity. Just try to stay on the good side of the Byzantines in the beginning.

You definitely want at least two herder's buildings. Cattle gives you a speed bonus to your cavalry, and goats are the best foodwise.

I always build two industry buildings, the yurt builder and the cloth maker. These give very good income. If you simply can't live without onagers, then build up the correspondent chain as well (this also gives extra ammunition to your horse archers so it's not a bad idea). I tend to skip any other industry buildings, unless needed for victory conditions.

As for military buildings, you only need one. And to be perfectly honest, in the beginning it only needs to be level 2. This gives you the Spet Xyons and the Steppe warriors. You might find yourself wondering whether you should go for Sogdian warriors or the Steppe warriors. My advice is to go for the Steppe warriors. I'd only take the Sogdians if the other option was Steppe tribespeople.
Later you'll probably want to upgrade the military building to a footmen's camp. This chain will ultimately give you access to Uar and Chosen Uar warriors. The other two military building chains (archers and lancers) don't really offer anything worthwhile. Spet Xyon are excellent horse archers that you will probably end up using for the rest of the game anyway, and hunnic shock cav selection is not amazing in my opinion. However, some victory conditions require these buildings so you'll probably convert your infantry encampment to one of these at some point.

The nomadic settlement building chain will give you Xionite spear at level 2, so this is a priority. Level 3 will give you the Hephthalite chargers, so you may want to rush building this if you feel like you need better melee cav to back up your horse archers. Level 4 gives you camel cav and unnigarde,both of which are pretty pointless in my opinion. However, if you want to diversify your army or just like camels, go for it. Not a priority though.

As for the rest of the buildings, you want to pick the ones that give you champions and spies. In my experience, the shamans tend to be quite useless for the White Huns, I simply hire them for the extra line of sight. However, research speed is always welcome, and you can get that from the shaman building chain. I always rush for champions, which I then position in my hordes to support them. Spies are invaluable when you start to engage the Sassanids, you simply have to know what may be lurking just a turn away from your hordes.

When you start to build your hordes, consider turning one into an economy focused horde. This horde can stay behind the front lines and focus on making money. There is no rush to get this horde to full stack, but you'll eventually want to engage the enemy with all hordes. For the beginning though, keep the economy horde safe and sound. Later on, you'll want all your hordes to be able to make both money, and good units, so pursue the economy horde strategy only in the beginning and only for one horde.

If you keep your hordes encamped at the ends of the turns, you should not be bankrupt. Never keep more then two hordes in the same region. The rivalry can get nasty. Two is still manageable, and you'll want to move in pairs anyway when you enter the Sassanid homelands.

Remember, White Huns gain nice income bonuses from raiding and sacking! Sack often. Raiding is only really worthwhile if you find a lucrative trade route to prey on. Most of the time it makes more sense to simply encamp.

When your armies and generals start to gain levels, you'll want to choose the upgrade paths that give you campaign map mobility, unit speed, sacking and raiding income and ammunition. Moralewise, you already have the upper hand against the easteners. As for the tech tree, try to keep a steady balance of researching both military and civil techs.

I didn't engage much in intra-faction politics and scheming. For my playthrough, I found a happy balance of power from simply appointing more generals from my own family than from the other nobles.

The early game is kind of slow. You will be mostly stationed in your starting province of Transcaspia, conducting assaults on the Sassanid vassals and retreating back to safety. The purpose for this is to gather your strength for the big push south.

First things first. You want a safe base of operations. You might as well turn Transcaspia into one. Afrighids and Parthians will be your first opponents here. Go to diplomacy and look at their leader's traits. If one of them looks like he might make a decent tributary go after them first and subjugate them. What you'll be looking for is things like : defensive, reliable, tolerant etc,. If it looks like neither the Afrighids nor the Parthians would make good slav- allies, feel free to destroy one of them, by razing their last settlement and killing their armies.

Now, what you'll do next is turn the remaining faction into a dairy cow. Siege their last settlement and conquer it. However, DON'T raze it. Simply sack it and station one of your hordes, preferably the economy focused one, nearby. Now what you'll do is allow them to rebuild their settlement to some extent and then sack it again. Just keep repeating this and soon your horde will have a nice experience level and integrity. Every now and then, a rebellion occurs and the rebels will conquer the settlement. Allow this to happen, then declare war on the rebels and start the process over. You can even take part in the battle if you are stationed close enough. When the rebels march in to the settlement, you might decide to "help" them by shooting them in the back with nasty friendly fire when they are engaged with the enemy. This way they will be nice and softened up for the next turn, when you turn on them.
EDIT: a helpful comment has brought to my attention that you in fact can not turn Parthia into a tributary since they are already a vassal to the Sassanids. However, what you can do is cause enough turmoil in their last settlement to cause a rebellion, and allow rebels to take over. Keep up the ruckus and another rebellion will occur to wrest the settlement from the rebels. If these counter-rebel-rebels win the result is an independent Parthia, which you can then turn into a tributary state.

While your economy horde is milking the cow, the two remaining hordes should start looking for new targets. The Sabirs and the Magyars have probably decimated Scythia and Hyperborea so I would advice you to go for Abarashar. Sack and raze to your hearts content, but if you start to see Sassanid BFF-stacks, run. With your two stacks you should be able to take on 4 of their stacks, but for now it might just be wiser to retreat back to Transcaspia, it is your home base of sorts. Remember, you are immune to desert attrition, so you might as well make use of the deserts in Khwarasan if you are forced to fight the Sassanids or their vassals. Return to hound the Sassanid vassals periodically, until you have destroyed Abarashar and Aria. Alternatively, you might want to subjugate one of them. Pursuing Makran may seem tempting, but you seriously risk pulling huge stacks against you, so I would hold off for now.

Next, start saving growth with your economic horde and spawn a new horde from it. When you have the new horde in at least half strength you might want to kill off the dairy cow. Either raze the settlement, or if their leader has agreeable traits, subjugate them. Next, you'll turn your focus on the Sassanids themselves.

You should now have four hordes, two or three of them full stack + the fresh one which should be at least half stack. It is time to take the war to the Sassanids. You are going to conduct war on two fronts, so divide your hordes to two pairs, with at least one of the hordes in both pairs in full strength.

Next, you'll continue to harass the Sassanid satraps to the south with one pair of hordes. Your primary targets here will be Atropatene and Makran, and the Sassanid towns and cities in Spahan and Persis. Don't be afraid to retreat if the odds are terribly stacked against you, but remember, you are immune to desert attrition, so this should be your home turf. You can take on several eastener stacks, especially if you've first led them a marry chase through the deserts. Easteners tend to field a lot of persian cavalry, cataphracts and armenian spears. Cavalry will melt away from your flaming ammo, leaving you free to pick out the infantry with the heaviest armor. Skirmisherwise, the easteners do not field anything that warrants special concern.

While one pair of hordes is busy harassing the Sassanids to the east, the other pair of hordes will swing round the Caspian sea and descend on the Caucasus from the north, the factions of Kartli and Arran being your primary targets. These are also Sassanid vassals, which means that taking them out weakens the empire itself. Be mindful of not angering ERE prematurely by attacking their allies in the area. If possible, try to turn either Kartli or Arran into a tributary state, this gives you another home base, this time in the Caucasus mountains, which is a nice retreat should things get too hot in the south (since these factions are Sassanid vassals you may have to resort to the same rebel-against-rebel-leading-to-an-independent-state -trick you may have used against Parthia) . Next, start harassing Armenia, which is arguably the strongest of the Sassanid vassals. Again, feel free to retreat to the safety of the mountains if BFF-stacks appear in unmanageable numbers. Having destroyed Armenia start to focus on Sassanid heartlands, and ultimately, Ctesiphon.

You can now pressure the Sassanid Empire from two sides. Continue putting the pressure on them. You might even get help from ERE. Eventually they will lose enough allies and regions to be able to maintain their armies, and they will start to suffer serious attrition. Once you have razed the Sassanid heartlands and Ctesiphon, the rest is just mopping up the remains. You might find that the remnants of the empire will be in the Arabian peninsula - quite a trek away. No matter -- desert immunity saves the day. Your four hordes will probably re-unite somewhere in the Mesopotamia. Don't keep them together for too long - what with the rivalry and all that.

Having finished of the Sassanids, clean up any smaller factions remaining in the East, Arabian peninsula, and Armenia. Sometimes, smaller factions may also arise in Cappadocia and Bithynia. You'll want to basically take out anyone who is not an ally of ERE. You might even be tempted to cross the sea to Aethiopia and take out Axum. If so, bring at least two stacks, as they can be feisty. In a related note, be very very skeptical about crossing any body of water. You are not a naval power and never will be.
Finally,make sure you do not anger the ERE before you're ready.

Having wiped out every living thing in the east (except for your tributary states), you will now turn your focus on the Eastern Roman Empire. These guys may turn out to be a bigger challenge than the Sassanids. During your conquest you should have amassed quite a lot of growth to your hordes. Use one of them and spawn a fifth horde. Start building it up.

What can the ERE field? Expect a lot of heavy spears and legionnaires. They do field cavalry but nothing compared to what you already dealt with when taking out the Sassanids. They do occasionally field strong skirmishers, which might become a priority target in large numbers. Occasionally you might also come across a stack with 6-8 onagers. While daunting at first, it is almost impossible to defend this many siege engines against a mobile army such as yours. Stick to the tactic of a stationary spearline and aggressive skirmishing and you should be fine. Against ERE, an army composition of 4 melee infantry and 2 spears also works, since the amount of cavalry the enemy fields is significantly lower than when you faced the Sassanids. Your Khingilas Khandas will hold their ground against comitatenses spears and eastern armoured legionnaires better then xionite spears. Remember, though, infantry alone will not win you the fight against ERE, always aim to finish the fight with your superior cavalry. The infantry line is there so that the enemy has a somewhere to go while you skirmish, and eventually rear-charge them. For this purpose, the Xionite spears will suffice, since you shouldn't let the infantry engagement last very long anyway.

The attack on ERE will take place through three fronts. Two stacks will be stationed in Aethiopia. Axum should either be destroyed or pacified to a tributary state prior to engaging ERE. You may face opponents like Egypt or Nobatia as well. Take care of them in a way which leaves ERE unsuspecting of any foul play. These two stacks will assault Alexandria and and nearby regions.

Two stacks will be stationed in Armenia-Cappadocia-Bithynia or thereabouts. Hopefully you will have a tributary state somewhere in the vicinity, Caucasus being a good choice. These two stacks will start engaging ERE settlements in Cappadocia, Cilicia, Bithynia and Asia Minor.

One stack will be stationed near Syria - Palestinae. The purpose of this stack is to assist the stacks in the north or south as need be, and to take out any targets of opportunity in the Levant.

Launch your assault and aim to take out at least one settlement from all three fronts during the same turn. The Aegyptian hordes will ideally take out Alexandria within a turn or two. The northern hordes will take out any nearby large city. The supporting horde in Levant will take out any tempting, poorly defended target, Edessa for example, while also in readiness to assist where needed.

You will now start to draw ERE stacks. Ideally their main military focus will be on one front. For me this was Aegyptus. Wherever they choose to focus on, be ready to retreat time and time again with the corresponding hordes. Fall back to the tried and true strategy of hit-and-run. In Aegyptus and Levant this is easy, since you are surrounded by deserts. In the north, however, the terrain is not in your favour and you should be more cautious in your movements. Always keep agents in the enemy territory so you know what may be approaching. It might be a good idea to use the two hordes in the north defensively, by allowing the enemy to come to you. You can always retreat to the Caucasus. You can also try to intercept any re-enforcements coming from Constantinople and heading south with the northern hordes. You will have to stay on your toes with the reserve horde in the Levant. Do not attempt to take well defended cities with just a single stack. If it starts to look like the northern or southern hordes need help, move in to assist with the Levant horde.

Your one true weakness is the ERE naval superiority. Never engage the enemy on sea, and only cross the waters if you are absolutely sure that NOTHING threatens your horde while crossing. This often means leaving some of the ERE island regions alone until later.

Eventually your hit-and-run tactics will start to pay off. For me, the turning point was a huge battle near Alexandria where I turned back six ERE armies. After that I managed to raze the whole of Aegyptus. Whichever front starts to falter, star rolling your hordes forward. If it is Aegyptus, start moving two hordes along the North-African coast, razing as they go. If the front falters in the north, wipe out everything on the eastern side of the Sea of Marmara. If Levant starts to falter, you may want to bring in the northern hordes to finish the job, especially if the enemy is strongly garrisoned.

Depending on what the Huns and the Goths have been up to, the Balkans might be a complete mess, or you might face a number of Roman allies. If you expect heavy resistance, bring in the Levant horde to assist. Two hordes should continue wiping out the African ERE settlements.

Eventually you will arrive at the gates of Constantinople. Lay siege and wait it out. Expect heavy casualties if you decide to assault the walls, even if only a garrison remains.

Congratulations, you have just destroyed the two most powerful factions in the game with five measly armies! Most likely, you have also already achieved at least the minor victory conditions. If you still feel like continuing, the world is your oyster. None of the remaining factions can really field anything that should worry you. In my game, the Danes had conquered half of Europe, so I went after them. Nordic and germanic armies are a dream to fight with the White Huns. Very little cavalry, and really crappy skirmishers.

WRE tends to be a complete mess in the late game. It is unlikely that they can resist you in any significant way. if they do, it will be much of the same stuff that ERE fielded.

The Huns are a variable. They left me completely alone in my campaign, and apparently achieved very little overall. Attila was dead and buried long before I arrived in Europe proper. However, the one thing that can truly challenge a well managed horse archer army is another horse archer army. So if you find yourself facing the Huns, you have to bring your A-game. If possible, try to maintain friendly relations with the Huns and other nomadic hordes.

Never trust your allies and tributaries too much. Quite often they will stab you in the back. The only faction that remained loyal and friendly to me from the beginning to the very end were the Sabirs, whom I never really met. Never ask your allies to join a war with you. They will hate you.

One of the biggest obstacles I faced was the massive Sassanid agent spam that awaited me in Spahan. I could not move my two hordes for several turns, and came really close to being destroyed when the BFF-stacks descended on me. What followed was one of the most intense battles I've ever had in any Total War game. So bring some spies of your own to thin the herd.

Overall, the White Huns offer some really satisfying moments and intense battles, where the existence of your entire faction often hangs in the balance. Fortunately, I honestly believe that the White Hun roster is the best in the game. Spet Xyon Archers and Xionite spears are pretty much the only units you truly need.

You can play them as pure horse archers, more melee focused, or as I did, an interesting mix of the both. Sometimes skirmishing was all that was needed to take out the enemy, but quite often it did come down to the Xionite spears holding the line and Spet Xyon charging to the rear. So it never truly got dull, as it often does with purely horse archer builds or melee builds.

The campaign offers a real challenge where you have to consider your moves very carefully and play it safe during one turn, and descend on the enemy ultra-aggressively during the next.