Alexander's Hetaroi
Deity
Well just to put in my opinion, I think that if we were to get another Civ from this region, Assyria is probably the more likely. It's a little farther away than Babylon would be from Sumeria and not already represented as a city-state that just came in last expansion.
As for uniques I can't really see them without their unique Siege Engine. It would probably be an earlier catapult replacement but be melee and do significant damage to city walls as well.
As for a unique infrastructure what about a unique first tier govt. building. A combination of Warlord's throne and an Ancestral Hall but gain the benefits of a settler whenever you conquer a city.
As for uniques I can't really see them without their unique Siege Engine. It would probably be an earlier catapult replacement but be melee and do significant damage to city walls as well.
As for a unique infrastructure what about a unique first tier govt. building. A combination of Warlord's throne and an Ancestral Hall but gain the benefits of a settler whenever you conquer a city.