When are empires considered to have collapsed?

Societal collapse (also known as civilizational collapse) is the fall of a complex human society characterized by the loss of cultural identity and of socioeconomic complexity, the downfall of government, and the rise of violence.[1] Possible causes of a societal collapse include natural catastrophe, war, pestilence, famine, and depopulation. A collapsed society may revert to a more primitive state, be absorbed into a stronger society, or completely disappear.

Explanation:

Often times, the biggest reason for the decline of an empire is that they have become overextended; either by reaching too far, too fast or by being forced, often times through economic need, to keep on capturing land.

Explanation:

they gained popular support by speaking out against communists

in the united states. ( d.)

racism and segregation.