The Assyrian diaspora refers to ethnic Assyrians living in communities outside their ancestral homeland. The Eastern Aramaic-speaking Assyrians claim descent from the ancient Assyrians and are one of the few ancient Semitic ethnicities in the Near East who resisted Arabization, Turkification, Persianization and Islamization during and after the Muslim conquest of Iraq, Iran, Syria and Turkey.

The Assyrian homeland, Assyria, refers to the homeland of the Assyrian people within which Assyrian civilisation developed, located in their indigenous Upper Mesopotamia. The territory that forms the Assyrian homeland is, similarly to the rest of Mesopotamia, currently divided between present-day Iraq, Turkey, Iran and Syria. In Iran, the Urmia Plain forms a thin margin of the ancestral Assyrian homeland in the north-west, and the only section of the Assyrian homeland beyond the Mesopotamian region. The majority of Assyrians in Iran currently reside in the capital city, Tehran.