Elam is the historical name for the region of south-western Iran closest to Iraq, covering both the mountainous area and the plain. It was anciently the region of the Elamite civilization, with its own language, which was written in cuneiform script for almost 2000 years. Uniquely, three distinct cuneiform writing systems were used in south-western Iran in ancient times: Mesopotamian cuneiform, writing various phases of Akkadian language; the adaptation derived from that used to write Elamite; and Old Persian cuneiform, invented to write this early Indo-European language.