Reply #1 Top
You must develop the right technology, I think it is called Alliances and you must also have a very good relationship with your potential ally. Worshipful or something like that. I know it is above calm, and friendly, but I haven't made an alliance since my first game so I don't remember the exact term.
Reply #2 Top
Close is the correct term. You can bribe the AI up to being Friendly, but after that they have to like you on your own. Trading with them helps; if their economy is dependant on you, they tend to like you more. :)
Reply #3 Top
Cari - thats an interesting tip (and knew to me) - bribery doesn't improve the relationship above friendly !?!

~SDC~