Note: Region along the Amu Darya in present-day Turkmenistan and Uzbekistan. Part of the Achaemenid Empire; conquered by the Arabs in the 7th century. From the 11th-13th centuries, ruled by the independent Khwārezm-Shāh dynasty. Became the center of the khanate of Khiva in the early 16th century. For a brief period after the Russian Revolution, the area was known as Khorezm People’s Soviet Republic.