I think the Mongols are a good idea. The only other town I might consider is Umma. I drew a map of a possible attack plan.
You place a town and bombard Umma with Artillery (this plan will be better with more artillery). Then take Umma and place a second town to move to the white border. The cities have hills between them and enemy which means the enemy cannot attack us on offense with tanks but do get the hill bonus (so we may want attack them after they retreat?) I kind of like the hills for a wall of defense though.
One advantage is that it takes away a saltpeter from the Sumeria. Not sure if that is important (it may only be so if they manage to get horses).
It needs to wait for 9 turns so there is no gap in the border between our current location and Umma, and may also have to wait for more artillery.
You place a town and bombard Umma with Artillery (this plan will be better with more artillery). Then take Umma and place a second town to move to the white border. The cities have hills between them and enemy which means the enemy cannot attack us on offense with tanks but do get the hill bonus (so we may want attack them after they retreat?) I kind of like the hills for a wall of defense though.
One advantage is that it takes away a saltpeter from the Sumeria. Not sure if that is important (it may only be so if they manage to get horses).
It needs to wait for 9 turns so there is no gap in the border between our current location and Umma, and may also have to wait for more artillery.

. Scoll ahead to avoid other mishaps. Enschede builds walls starts a temple. Kill 2 sumarians behind the lines but lose another healthy vet cav in the process to a redlined rifle. We are low on cavs again
. Kill 2 redlined rifles behind the lines and promote 1 infantry to elite. Kill 1 redlined Aztec rifle and an aztec Cav. Wound a huge stack of Bab units outside of Bactra.
Why did we rush a factory in a city that needs a courthouse? Is this one of those one shield short deals?