During World War I , the British occupied much of the territory of western Iran , and fully withdrew in 1921 . Meanwhile , a famine in northern Iran killed between eight and 10 million people . The Persian Campaign commenced furthermore in northwestern Iran after an Ottoman invasion , as part of the Middle Eastern theatre of World War I . In the course of the Assyrian Genocide of 1914 – 1920 and the Armenian Genocide of 1915 – 1917 , a large number of Iranian Assyrians and Armenians were subjected to mass murders committed by the Ottoman troops that were crossing the northwestern border , notably in and around Khoy , Maku , Salmas , and Urmia
Armenian Genocide
Armenian Genocide
Iran