What causes AI's in SP to declare war?

[Nappa]

I'm trying to win in SP with every race on the orania nasty map. I'm currently playing Jutenheim and I'm having trouble.

For the second game in a row on this map I'm having numerous races declare war on me early in the game.

On turn 5 man declard war (who cares, he's not near me) A couple of turns later Atlantis declared war. So I'm fighting Atlantis when on somewhere around turn 10 Caelum declares war on me.

I'm fighting Atlantis and Caelum and barely holding when last turn (turn 20) Marignon and Vanheim both declare war and attack. Game over.

This has happened twice now. Does the computer choose based on the quantity of units in play? If not then how?