Midak

Overall strategy
Midak form the lesser nobility of Tibet, the rest being either the most powerful aristocrats or the clergy, considered to be second in power only to the monarchs themselves. Unsurprisingly, they in combat often have the best armour and weapons, and so form a shock cavalry component in the early game., thus allowing the Tibetans to defend against light cavalry whilst providing them the ability to punish lighter units, especially Tibetan Spearmen.

Midak are useful in that they ensure that Tibet doesn't just train heavy cavalry off the bat (the Constabulary is requried for the Sde Dpon instead)  but also has a unit that has elevated resistance to foot infantry units, thus making Midak very difficult to kill except with dedicated cavalry of your own.