Quote Originally Posted by The Celt
It's pretty easy in theory. It just requires the BI.exe and you have to copy some of the units of those factions(Same as the regular unit, except it's got a little wheel on it's icon. ) and that may be where it gets tough. Since EB's hitting pretty close to the unit limit as is, I don't know how you'd be able to horde the Nomads AND the Celts. It would be cool tho, if the one of the Nomad factions emgered on a certain and they'd be like the Mongols in MTW.(maybe have the Saka be the one steppe faction and the Sarmatians emerge from them?)
Why do that? It'll just mean you can't play as the sauromatae.