Because non-communist governments wanted to control its spread, and prevent other countries from becoming communist. I guess because communism's style of governance is unfair to some.
Manifest destiny. They believed it was their god given right to expand westward.
Answer:
The Tito–Stalin split, or the Yugoslav–Soviet split, was the culmination of a conflict between the political leaderships of Yugoslavia and the Soviet Union, especially under Josip Broz Tito and Joseph Stalin, in the years following World War II. ... Stalin tried to pressure and moderate Yugoslavia via Bulgaria
I would say the Hittites and the Celts. The Hittites thrived and disbanded before the beginnings of the Roman empire. The Celts were absorbed by the Romans but were keen to follow their ways.
jew..........................
