Before they settled in the Carpathian Basin, the early Hungarians came from the Uralic regions, and they had nomadic personalities.
Them having Steppe Lancers emphasizes two things: 1) their expertise as nomadic horsemen and 2) Other nomadic tribes assimilated in Hungary (Kabars and also take the Cumans, they sought asylum in Hungary from Mongol invasions)
So in a imperial age army, you can either back Magyar Huszars with heavy infantry and cavalry, or a nomadic style army of CA, hussars and Steppe Lancers. who also fancies a discount on Steppe Lancers?
Bulgarians
The Volga Bulgars who settled in Russia were also nomads just like the early Magyars, so use of Steppe Lancers could be justified.
As for the Bulgarian Empire, Cuman refugees that escaped from Mongol invasions assimilated in Bulgaria as well as Hungary.
If it weren’t for the Cuman-style masks that the Elite SL wear, Turks and Huns could get them too. Turks
The Seljuk Turks came from Central Asia and migrating westward. Them having Steppe Lancer also reflects their highly skilled nomadic status.
Sure but Bulgarians should be renamed to Bulgars, it’s not aoe3. As Magyars are not Hungarians yet.
And I’d rename Turks to either Seljuks or Ottomans since there are like dozens of Turks in the middle ages.
It could be interesting, but I think some of them should lack the Elite Steppe Lancer.
Persians could also receive this unit, they were geographically and culturally connected to the Central Asian steppe and had strong cavalry traditions.
I guess the Bulgarians and Lithuanians if they get the unit. Maybe the Magyars if the Corvinian Army UT replace their gold cost with food cost so someone would get trash steppe lancers.
EDIT: The Hindustanis could also receive the non-elite Steppe Lancer, as their ruling class and parts of their army came from Central Asia.
First of all, because among the 4 civs they are the ones that more desperately need a bit more variety on their roster.
Second, all those civs represent a culture that started as nomadic, but settled at some point, and focus more on the settled part of their history. The Huns instead never settled, and they works as the archetype of the european steppe civilization of late antiquity.
They could benefit from the 10/20% discount in castle/imperial age, and the 20% faster working stables. If they would be OP, then remove or reduce the discount.
Persians should probably be added to the list. And Gurjaras even have a claim to them, thanks to the Hunas influencing their military over the years of conflict and then occupation.