What about the Indogreeks or something like Gandahara kingdom, they will start Indian and become Helenized after reforms. I remember a faction emblem with ichtyokentaur (the beast that Indohelenic noble hoplite has on shield) in one of EB1 previews. As shown in EB2 previws EB team did great job in implementing new features like culture buildings and nomad camps, so perhaps factions on the edge of the map won't be problem.