Typical AI behaviour:
1. They grab land. Any land. If they see an open piece of real estate they will build a city on it. From my experience in playing the Regent level they grab everybody's land, including other AI civ's land.
2. They trade techs a lot amonst themselves. So if 1 civ has a tech, very soon all the others will have it. If 1 civ got a tech from a hut, then very soon everybody will have it. That's probably why they have more techs than you.
3. They trade maps a lot. That's probably why they have more knowledge of the world.
4. They like to gang up on somebody. In this case its you. Yes in my game I was fighting a grand alliance of 7 AI civs as well. But I admit that I have almost ignored diplomacy, have seldom traded, have always refused to pay tribute, and I started the fight

. I have read reports from other players that he could unit 6 AI civs to wipe out the last one though. Maybe we can do better next time