I could provide my own story of Gilgamesh of the Sumerian Empire who was blocked in by the borders of the One Great Indian Nation ruled by Asoka (my civ). In this game (my most recent) I was going through a series of wars, but never once have I declared, or been declared on by Gilgamesh, despite the -2 penalty for our close borders sparking tensions. Instead, I maintained good diplomatic ties with him, and a net modifier of +13, and him being quite pleased with me. It went higher, I know that, but when I fired up the save just now, there have been some modifiers that obviously went away, mostly random events, but also religion bonuses too. I should add that this game is right into the modern age now.
As I recall, we (albeit fortuitously) managed to share the same religion founded by someone else on the continent, his favourite civic was hereditary rule, which I was happy to use given my militaristic pushing I was doing, and I kept tabs on who his enemies were, and played the random events as they came up to ensure good relations. At any point, I could have rightly crushed him military wise, but he was more useful as a buffer on my south. And it was all tundra, crap place to build cities generally, let alone support.
But it wasn’t just Gilgamesh, I took the time and weighed up the whole diplomatic picture with most of the leaders on the continent, and made the decisions on who was the most powerful, who would likely be destroyed, or what wars would likely come up. It involves more than just building stuff, moving units around, researching a tech and pressing end turn, and seeing what happens. After the city info window (F1), I would say the diplomatic window is the next most powerful information tools in the game.
Gameplay can easily be affected by the people around me. I never got that in Civ V. All I got was a passive AI that was happy to leave me out of the picture. I never felt as though I had to go to war to aide an ally. In fact, I was happy to tell them to bugger off most of the time. Unless they attacked me, my only real diplomatic interactions was the initial meeting, or whatever weak arsed offers they’d provide.
In the link I provided in my last post, there are 25 items that will affect the civilisation’s attitude toward the player, some visible, some not in Civ IV. That is a lot to deal with. To complicate matters in Civ IV, I’d play with randomised leader personalities. Having Montezuma as a peaceful sort makes for a nice change. But it also means I have little to no idea how the AI will actually treat me, whether they will go to war at the drop of a hat, or to build their own empires quietly in the background.