Everytime I make a peace treaty it can be broken right away
I hate pointing out other games, but this has been an issue/exploit that both the AI and I can use (and the AI uses it all the time): Get a peace treaty , and extort techs/money out of opponent. Wait 3 turns (or less). Attack. Rinse and repeat.
In Civ4, if you sign a peace treaty, you have to wait 10 turns (i think its 10 turns) before you can attack again.
If you give tribute as a means to secure a peace treaty (either you OR the AI) you should have at least some sense of security they won't attack the next turn or two.