Okay, I edited my previous post.

Well I didn't remain allied with the Seleukids because in a previous failed campaign, they back stabbed me very early on anyways (within the first 10-15 turns). So in my new campaign, I didn't bother holding on to my alliance with the Seleukids.

Really the problem here is one of diplomacy...how is it that the AI is able to negotiate ceasefires and alliances without much of a problem, while it is much harder for a human player to negotiate successful treaties (let alone maintain them)? Keep in mind that I am talking about an early game situation, where I don't have an experienced diplomat, or gold in the coffers to appease enemies with.