You could use the 300 BC scenario made by Thorgal, the diadochi wars as base for city placement and civs. Its a scenario made for the pie_at PAE mod. It´s quite accurate. Its good to see so much celts and gallic civs, but i see too few in the east. Galatians (i think the gauls went to Anatolia before 260, but not sure), Pontic, Dacians, Ptolomeic egiptians, perhaps Parthia, Nubia depending the map.