Natives

[KJIOYH]

Update.

Getting cultural pops actually helps relations. I had -6 for stealing land after i captured a european city, then after 1 pop of nearby city it dropped to -2, after second from the captured city it dropped to 0

 

[doron]

I had a game where one tribe I was close to started attacking and had to wipe them. Logan, who was always friendly, switched to annoyed (no close settlements) in about 10-15 turns and declared war. Perhaps attacking natives causes others to become less friendly (though no special modifier was shown)