By forming various organizations.
The European Union, for example, unites Europe (Minus Britain these days) under one banner, thus preventing fighting.
A more direct example is the North Atlantic Treaty Organization. NATO protects the "North Atlantic" and Europe from terrorists and invading countries by using the combined military strength of multiple nations.
According too the nebular hypothesis Helium and hydrogen
A government controlled by the people is called a democracy. <span />
A. The Soviet Union became an ally of the United States and Great Britain during World War II.
