I was playing on regent as Vikings and started from continent with Babylon,America and Korea. I expanded normally and at 600 b.c i saw american warrior/warrior pair coming towards my city and soon after they declared war on my territory. They was long jungle inbetween us, so they were not a problem and i made peace with them a bit later. Soon i noticed that babs border were right next to me and they seemed to be rather weak, so i gathered archers/horsemans and declared war on them while all my troops were on my territory. I razed about three cities to make space for my cities and prevent cultural flipping and after that they were ready for peace. Few hundred years later i had some new contacts with new civs and i was trying to sell something for per-turn gold deal (with them paying) and my advisor said "They would never accept such deal" and I've no idea why..? 
EDIT: I've not done any per turn deals before on this game, so i can not have broken any.

EDIT: I've not done any per turn deals before on this game, so i can not have broken any.