Saka reformed units

[keravnos]

You must hold Baktra, Marakanda, Alexandreia Eschate, Antiocheia Margiane, Alexandria Ariana or Taksashila for 4 consecutive winters.

On them you must build an allied government.

here is the FAQ
http://www.twcenter.net/forums/showthread.php?t=97258

[Tristuskhan]

Well, I've been playing a bit more and was quite unsuccessful gaining access to new units (only Sampol infantery in Bactra, that's a pity....). I took Antiochia-Ariana recently, built "indigenous settlements" but am unable to upgrade to "allied government". Maybe I must wait for the famous "four winters", I don't know... The only place (out of ten provinces) where I was able to build allied government is Kophen, and there seems to be no local unit available.

[Ravenic]

Yeah, you 'kinda need to wait for the 'famous four winters', because that's what the FAQ (And I) said in the first place.