I noticed that on easier difficulty levels < normal I was able to pretty much get away with not trading with other civs. On normal difficluty and above, it seems that you MUST trade or all the other civs will come at you-- good or evil. Other than extra income from the trade revenue why does it seem that you HAVE to trade or set up lots of trade routes? Do the computer players treat this as hositle so that they come at you eventually (nearly all at once )? Have any of you won at the higher levels w/o trading?