Lake Urmia is an endorheic salt lake in Iranian Azerbaijan, Iran and near Iran's border with Turkey. The lake is between the provinces of East Azerbaijan and West Azerbaijan in Iran, and west of the southern portion of the Caspian Sea. At its full size, it was the largest lake in the Middle East and the sixth-largest saltwater lake on Earth with a surface area of approximately 5,200 km² (2,000 mile²), 140 km (87 mi) length, 55 km (34 mi) width, and 16 m (52 ft) depth. The lake has shrunk to 10% of its former size due to damming of the rivers that flow into it and pumping of groundwater from the area.
Lake Urmia, along with its once approximately 102 islands, are protected as a national park by the Iranian Department of Environment
One of the early mentions of Lake Urmia is from the Assyrian records from 9th century BC. There, in the records of Shalmaneser III (reign 858–824 BC), two names are mentioned in the area of Lake Urmia: Parsuwash (i.e. the Persians) and Matai (i.e. the Mitanni). It is not completely clear whether these referred to places or tribes or what their relationship was to the subsequent list of personal names and "kings". But Matais were Medes and linguistically the name Parsuwash matches the Old Persian word pārsa, an Achaemenid ethnolinguistic designation.
The lake was the center of the Mannaean Kingdom. A potential Mannaean settlement, represented by the ruin mound of Hasanlu, was on the south side of the lake. Mannae was overrun by the people who were called Matiani or Matieni, an Iranian people variously identified as Scythian, Saka, Sarmatian, or Cimmerian. It is not clear whether the lake took its name from the people or the people from the lake, but the country came to be called Matiene or Matiane, and gave the lake its Latin name.
The Battle of Urmia was fought near the lake in 1604 during the Ottoman–Safavid War of 1603–18
In the last five hundred years the area around Lake Urmia has been home to Iranians, Assyrians, and Armenians.