dh_epic said:
I think drawing lines through a complex combination could be interesting:- current government
- geography-link
- culture-link (ethnicity)
- religion
- history
I do agree, but I will try to put a more technical and simplistic theory on it. I call this phenomenon "Us vs. Them". It is one of the few priorities that on the most basic level determine the actions of nations.
The question always is, who is Us and who is them.
Us is anybody who shares a common something that the them do not. Often that is ehtnicity, religion, realtive geography, maybe even a history of being a former colony. The them is those who threaten whatever the Us is.
To make it a little less abstract, example pre-Alexandrian Greece. The Greek city-states were very independent and often fought between each other. At that moment, the Us was the particular city-state and its allies(econmic and historically) and the Them was those whose resources and power Us wanted. For here, the Us and THem are Athens and Sparta.
Now Persia mounts an invasion of Greece. Another set of Us and Them emerge. The Us is Greek peoples of the Greek religion. The Them is the Persians, who are of a different religious and cultural and historical background.
The Us and THem of Athens and Sparta still exist, but alongside the Us and Them of Greece and Persia. Now both Athens and Sparta have to decide which Them is a greater threat. In history they said that Persia was a stronger them then each other. Once Persia was defeated at Salamis, they were no longer as great a threat. Athens and Sparta are now on opposite sides again.
Civ AIs forget that their people hold their unique cultural and religious heritage very closely. So they should try to protect any threats to those values. That may mean helping out a hated enemy of the same background because that attack will eventually hurt your background. The states of Europe during the middle ages hardly had any love between them. HOwever, Islam was considered a greater them(for profit reasons) then each other.
This is a hard model to impliment, so pick my argument at will. As well as my atrocious spelling and grammar.