Italy, facing opposition to its wars in Abyssinia (Ethiopia) from the League of Nations, forged an alliance with Nazi Germany, which had withdrawn from the League in 1933. The term was first used by Benito Mussolini, in November 1936, when he spoke of a Rome-Berlin axis in reference to the treaty of friendship signed between Italy and Nazi Germany on October 25, 1936. Later, in May 1939, this relationship transformed into an alliance, dubbed the "Pact of Steel".
The Axis was extended to include Japan as a result of the Tripartite Treaty of September 27, 1940. The alliance was subsequently joined by Hungary (November 20, 1940), Romania (November 23, 1940), Slovakia's puppet government (November 24, 1940) and Bulgaria (March 1, 1941).
Yugoslavia joined on March 25, 1941, but a British-supported coup d'état two days later put Yugoslavia's participation in question (although King Peter II of Yugoslavia actually declared his adherence to the treaty), leading to a Nazi occupation of Yugoslavia in April.
In Allied usage, Finland was often referred to as an Axis country, but it was never a signatory. Finland characterized its relationship with Nazi Germany during the Continuation War as co-belligerence.
Some Italians born in this time were named Roberto, which briefly acquired a new meaning from "Roma-Berlino-Tokio".
See also: Central Powers