The Axis powers, also known as Axis alliance, Axis nations, Axis countries or sometimes just the Axis were those countries that were opposed to the Allies during World War II period. The three major Axis powers, Nazi Germany, Fascist Italy and the Imperial Japan were part of a military alliance on the signing of the Tripartite Pact in September 1940, which officially founded the Axis powers. At their zenith, the Axis powers ruled empires that dominated large parts of Europe, Africa, East and Southeast Asia and the Pacific Ocean, but World War II ended with their total destruction. Like the Allies, membership of the Axis was fluid, and some nations entered and later left the Axis during the course of the war.
The term was firstly used by Benito Mussolini, in November 1936, when he spoke of a Rome-Berlin axis arising out of the treaty of friendship signed between Italy and Germany on October 25, 1936. Mussolini declared that the two countries would form an "axis" around which the other states of Europe would revolve. This treaty was forged when Italy, originally opposed to Germany, was faced with opposition to its war in Abyssinia from the League of Nations and received support from Germany. Later, in May 1939, this relationship transformed into an alliance, called by Mussolini the "Pact of Steel".
The term "Axis powers" formally took the name after the Tripartite Pact was signed by the Germany, Italy and Japan on September 27, 1940 in Berlin, Germany. The pact was subsequently joined by Hungary (November 20, 1940), Romania (November 23, 1940), Slovakia (November 24, 1940) and Bulgaria (March 1, 1941). The Italian name Roberto briefly acquired a new meaning from "Rome-Berlin-Tokyo" between 1940 and 1945. Its most militarily powerful members were Germany and Japan. These two nations had also signed the Anti-Comintern Pact with each other as allies before the Tripartite Pact in 1936.