Mass deportation of Azerbaijanis from Armenia took place several times throughout the 20th century, and sometimes some of them have been described by some authors as acts of forced resettlement and ethnic cleansing.
Prior to the October Revolution, Azerbaijanis had made up 43 percent of the population of Yerevan. The Tartar (i.e. Azerbaijani) population endured a process of forced migration from the territory of the First Republic of Armenia and later in the Armenian SSR several times during the 20th century. Under Stalin's policies, approximately 100,000 Azerbaijanis were deported from the Armenian SSR in 1948. Their houses were subsequently inhabited by Armenian repatriates who arrived in the Soviet Union from abroad.
Azerbaijanis continued to live in the Armenian SSR until the outbreak of the Nagorno-Karabakh conflict in 1988–89, when practically all Azerbaijanis in Armenia left or were expelled concurrently with the expulsion/flight of Armenians from Azerbaijan. The deportation was done largely without bloodshed and it was partially in response to Armenians being forced out of Azerbaijan; it was also the last phase of the gradual homogenization of the Armenian republic under Soviet rule.
Beginning of the 20th century
As a result of Armenian-Azerbaijani interethnic conflict in the beginning of the 20th century, as well as Armenian and Azerbaijani nationalists' coordinated policy of ethnic cleansing, a substantial portion of the Armenian and Azerbaijani population was driven out from the territory of both Republic of Armenia and Republic of Azerbaijan. Starting in the middle of 1918, Armenian paramilitary forces under the leadership of General Andranik Ozanian destroyed Muslim settlements in Zangezur (the southernmost part of modern-day Armenia). The British command, which had its own political objectives didn't allow Andranik to extend his activity to Karabakh. Andranik brought 30,000 Armenian Genocide survivors from Eastern Anatolia in the Ottoman Empire, mainly from Mush and Bitlis. Part of Armenian refugees from the Ottoman Empire remained in Zangezur, whereas many others were settled in regions of Yerevan and Daralagoz, where they took the place of outcast Muslims in order to making Armenia's key regions ethnically homogeneous.
Soviet Armenian historian and Bolshevik politician Bagrat Boryan charged that the ARF had not established state authority for the administrative needs of Armenia, but for the “extermination of the Muslim population and looting of their property”. According to data from Caucasian Ethnographical Collection of Academy of Sciences of the USSR, "the settlements of Azerbaijani population in Armenia had become empty." Nataliya Volkova writes that the ruling party of the First Republic of Armenia, the ARF-Dashnaktsutyun, followed a "policy of 'cleansing the country from outsiders'" which "targeted the Muslim population, especially those who had been driven out from Novobayazet, Yerevan, Echmiadzin and Sherur-Daralagoz districts. Volkova writes:
In 1897, out of the 137.9 thousand people living in Zangezur uezd, 63.6 thousand was Armenian (46.2 percent), 71.2 thousand was Azerbaijani (51.7 percent), 1,8 thousand was Kurdish (1.3%). According to agricultural census of 1922, the whole population of Zangezur was 63.5 thousand people, including 59.9 thousand Armenians (89.5%), 6.5 thousand Azerbaijanis (10.2%) and 200 Russians (0.3%).