I would like to suggest that we ban the gifting of cities to any AI factions as it is possible to exploit the game in this fashion when playing as the Romans.
The Senate AI is programmed to send its army to attack any unfriendly army that enters 1 turns march of ROME. If you give another city to the Senate then the same behaviour will apply here and so it is possible to get the Senate`s overpowered army at the start of the game to cause mass deathy and destruction. Ive done it plenty of times myself in SP. Believe me this Senate army is impossible for any army at the early stages of the game to stop.