Thats what makes me think it was a respawn rather than a settlement. I'm not sure if I have a save of around that time to look at but the terrain wasnt special, BG but no wheat or cows so growth couldnt have been phenomenal. Its sort of possible it was just lost in FoW until I killed the other city which was definitely showing a capital flag.
Hmm, I don't think the AI can rush several units and a settler in one turn, on any level. I'd rather say it was one of the following:
- The town and the units were already there, but were hidden in the FoW, so you didn't see it yet. If you have an embassy with a civ, and you destroy their capital, and the capital jumps into a FoW area, then it becomes visible to you immediately, because of the embassy.
- The area was already discovered by you (so no FoW) and the settlers / stack of units were already there, but not visible to you. Then in the turn you destroyed their last town, they did not die (because still had a settler), and in the interturn the settled a new capital, which became visible to you.
- It was indeed a "real respawn" and the rules of respawn are such that they start with more than just a settler/worker pair?! I've never played with respawn on, but it would make sense to give them more units, otherwise they would die again right away...! I wouldn't be surprised, if the respawn worked in such a way that it depends on how far everybody else is advanced. For example the game could look at the currently weakest civ and then give the respawned civ the same amount of units, techs and settlers as that weakest civ. (Might be an interesting research project to discover the rules of respawning...! Well, never mind: AI respawn rules)