Uther the unhinged over on Chaos Dwarfs Online had ideas to share (yaks are not southeast Asian creatures, but poetical fantasy license could have yaks brought down from the Sky Mountains, and maybe bred for shorthaired versions):

Quote Originally Posted by Uther the unhinged
Their peak weapon could be a mechanical Chinese dragon. Could be a golem pr part armoured personnel carrier, winding across the battle field breathing fire then disgorging dwarves to assault the enemy.

If you want a a less tNot sure of the History and geography here but would they have Yaks? Armoured Yaks would be awesome. Certainly mountain goats could provide cavalry with crossbow wielding dwarves on their back. These would be perfect for the hit and run warfare against the infernal dwarves. The repeating crossbow was a Chinese inventing so might be appropriate too.

Gunpowder would fit. To distinguish them from their infernal cousins no fire arms or steampunk but how about hand held bombs, the old cartoon round things with fizzing fuses. Rockets too, but small scale easily portable. Maybe mortars but again small scale. I am thinking of the old ?3rd ed chaos dwarf 2 man(dwarf) mortar team.

The thinking behind this (other than the dragon) is that their traditional homelands do not lend themselves to large scale open warfare. Similarly any attempt to hold back the massive imperial armies from the Easton open battle would have been catastrophic. Therefore these mountain dwarves would have developed a style of warfare(above ground) of rapid hit and run guerrila style. Think of the wars in Afghanistan over the centuries. So you would have fixed phalanxes of heavy armoured dwarves for below ground warfare but rapid moving/mobile forces above. Goat riding cavalry, hopefully an excuse for yak residing heavy cavalry. Grenadiers, small 2dwarf mortar or rocket teams, maybe with a goat or yak attached so the could fire and move rapidly to new positions

What do you think? I could be biased in my thinking coz I want yaks!