The indigenous Assyrian homeland areas are "part of today's northern Iraq, southeastern Turkey, northwestern Iran and northeastern Syria".[63] The Assyrian communities that are still left in the Assyrian homeland are in Syria (400,000),[64] Iraq (300,000),[65] Iran (20,000),[66][67] and Turkey (15,000–25,100).[66][68] Most of the Assyrians living in Syria today, in the Al Hasakah Governorate in villages along the Khabur river, descend from refugees that arrived there after the Assyrian Genocide and Simele massacre of the 1910s and 30s. Christian communities of Oriental Orthodox Syriacs lived in Tur Abdin, an area in Southeastern Turkey, Nestorian Assyrians lived in the Hakkari Mountains, which straddles the border of northern Iraq and Southern Turkey, as well as the Urmia Plain, an area located on the western bank of Lake Urmia, and Chaldean and Syriac Catholics lived in the Nineveh Plains, an area located in Northern Iraq.[69]