The power of a nation state to determine its own government is called

The power of a nation state  to determine its own government is called: SOVEREIGNITY.

The word "Sovereignity" arises from the Latin superanus, meaning "chief" and the Latin regnum, meaning "kingship". It is the full right and power  that a country has to govern itself or another country or state, without any interference from outside sources or bodies. In political theory, sovereignty is a substantive term designating supreme authority over some polity.

treaties

explanation:

it was on the rise and doing very well and would continue to do well until the great depression from 1929-1939