Gone, but not forgotten?

Post-patch, the AI civs seems much more aggressive. I started a new game and am seeing a lot of early wars. In one case, Barre's capital was quickly captured by Daoming's forces.
I was surprised, but didn't take too much notice.

A few turns later, I notice on the diplomacy screen that Daoming is still at war with Barre. However, there is no way for me to contact him. Does this mean he is still in the game, but I have to find his city or cities before diplomacy is possible? Or is it simply a glitch?

 

I believe what's happening is that his new capital is a location you haven't seen yet and thus you can't talk to him (even if you met him before I guess)

 

Both of my neighbours (Apollo) declared war on me on turn 80 and I couldn't get a piece treaty for the rest of the game, even after capturing all but one of their cities.
Of course, it messed up my whole trade network and it felt buggy overall.