VI, but
>playing Poland on island plates
>spawn on the same island as the Aztecs
>not sure whether I want to war with them, forward settle and begin killing the barbarians on their borders
>the barbarian camp in an awkward position and the Aztecs end up in a perfect position to clear it despite me doing all the work
>decide to declare war to lure them away from the camp
>open the trade menu to see if I can't unload steal some of their gold
>they have a relic
>Poland wants relics
>they refuse to trade it, not even for all of my gold and luxuries
>fuck it, war
>very quickly realize that we're the only two civilizations on a relatively small island
>worse, realize that there's mountain range dividing the island in half between the two of us
>two one-tile chokepoints, one of which is occupied by a city
>it takes an entire era to break through and capture their capital
>by the time the war is over, we're both completely irrelevant
>it took so long that I forgot about the relic
>two eras later, the Mayans offer it to trade it to me out of the blue
One little annoyance started a war that lasted hundreds of years and wiped out an entire civilization, yet I didn't even remember what started it. I assume he sold it for gold to pay for his units toward the end.