Iranian Armenia (1502–1828) refers to the period of Eastern Armenia during the early-modern and late-modern era when it was part of the Iranian empire. Armenians have a history of being divided since the time of the Byzantine Empire and the Sassanid Empire, in the early 5th century. While the two sides of Armenia were sometimes reunited, this became a permanent aspect of the Armenian people. Following the Arab and Seljuk conquests of Armenia, the western portion, which was initially part of Byzantium, became eventually part of the Ottoman Empire, otherwise known as Ottoman Armenia, while the eastern portion became and was kept part of the Iranian Safavid Empire, Afsharid Empire and Qajar Empire, until it became part of the Russian Empire in the course of the 19th century, following the Treaty of Turkmenchay of 1828.