The relationship went bad because of England wanting to repay its war debts by increasing taxes on the American colonists.
The Black Power movement led by Malcom X had ideas similar to King's movement, being that they both wanted rights for African-Americans, but the way they protested is where they differed. Malcom X criticized MLK's method of peaceful protest, and took to having a more radical and violent way of protest and fighting back against oppression. I hope this helps :)
North Africa traded gold while the west Africans traded salt, so they each benefited