My recollection from the old Soviet days was that the Russians made noises about solidarity with oppressed black folks in Africa, brought them to Moscow for training in communism -- and then treated them like dirt.
Some things don't change.
You're right.
Correct. Add to it that those brought-in foreigners were afforded privileged treatment [vs. regular guy-on-the street] which obviously added to the resentment. "Lumumba University of Friendship Between the Peoples" [the main institution these were organized in] was popularly known as "Lumumbarium".