In August–September 1941, Pahlavi Iran had been jointly invaded and occupied by the Allied powers of the Soviet Red Army in the north and by the British in the centre and south.

[7] Iran had long been torn between the bordering zones of influence of Britain and Russia, but had managed until then to remain independent, despite several foreign interventions, by taking advantage of the rivalry between the two rival powers.

As a result, Rezā Shāh was forced to abdicate on September 16, 1941,[6] and exiled to Mauritius; his son, Mohammad Reza Pahlavi, the crown prince, became the new monarch.

Their joint 'Tripartite Treaty' of January 1942 declared that their military presence was not an occupation, proclaimed Iran to be their ally, and pledged to withdraw their troops within six months of the end of the war.

At the Tehran Conference in 1943, the Big Three gave additional assurances concerning Iran's future sovereignty and territorial integrity, as well as a promise to assist in its post-war reconstruction and development.

The Azerbaijani Democratic Party (ADP) was formed in September 1945 and headed by Jafar Pishevari, a long-time leader of the revolutionary movement in Gilan.

[10][11] Later in September 1945, at its first congress, the Azerbaijani Democratic Party authorized the formation of a peasant's militia, which by mid-November 1945 captured all remaining government posts in the province, and Iranian Azerbaijan "became an autonomous republic under the direction of a 39-member national and no executive committee".

[citation needed] Though the Soviets initially supported the new autonomous entity and prevented the Iranian army from restoring governmental control over the area, it did not last for long.

Despite Soviet opposition, Mullah Mustafa Barzani came to play an important role in the newly created military force of the Mahabad Republic – the Peshmerga.

With Barzani's support secured, along with some 60 tribal Kurdish leaders, the KDP-I party platform had been established and Qazi Muhammad was elected the first president on January 22, 1946.

On June 15, 1946, this period of preparation ended, as the fighting positions of the Second Kurdish Regiment at Mamashah (Mil Qarani) were attacked by two Iranian battalions supported by artillery, tanks, and aircraft.

The Barzanis, including the Peshmerga and their families, withdrew to Naqada on December 15, 1946, and the Iranian military entered Mahabad, officially ending the one-year life of the Kurdish Republic.

In various battles throughout mid-March, the Peshmerga defended themselves against numerous offensives as Iranian forces continued their attacks, often recruiting rival Kurdish tribes to oust the Barzanis.

However, with his forces withering under the continuous attack, Mustafa Barzani realized the need to flee Iran and cross the border into Iraqi Kurdistan.

Following an official U.S. protest, the United Nations Security Council passed Resolution 2, on January 30, 1946; the Soviets replied on March 24, 1946, and pledged immediate withdrawal, but in fact remained for a few more weeks.