The Rann of Kutch is a seasonally marshy region located in the Thar Desert biogeographic province in Gujarat state of northwestern India and the Sind province of Pakistan. The name "Rann" comes from the Hindi word ran (रण) meaning "salt marsh". The Hindi word is derived from Sanskrit / Vedic word (इरिण) attested in the Rigveda and Mahābhārata.
Kutch is the name of the district wherein it is situated. The Rann of Kutch comprises some between the Gulf of Kutch and the mouth of the Indus River in southern Pakistan. The Luni River, which originates in Rajasthan, empties into the northeast corner of the Rann.
In India's summer monsoon, the flat desert of salty clay and mudflats, averaging 15 meters above sea level, fill with standing waters, interspersed with sandy islets of thorny scrub, breeding grounds for some of the largest flocks of Greater and Lesser flamingoes. At its greatest extent, the Gulf of Kutch on the west and the Gulf of Cambay on the east are both united during the monsoon.
The area was a vast shallows of the Arabian Sea until continuing geological uplift closed off the connection with the sea, creating a vast lake that was still navigable during the time of Alexander the Great The Ghaggar River, which presently empties into the desert of northern Rajasthan, formerly emptied into the Rann of Kutch, but the lower reaches of the river dried up as its upstream tributaries were captured by the Indus and Ganges thousands of years ago. Traces of the delta and its distributary channels on the northern boundary of the Rann of Kutch were documented by the Geological Survey of India in 2000.
This inhospitable salty lowland, rich in natural gas and a resting site for migratory Siberian birds, is part of India and Pakistan's ongoing border dispute concerning Sir Creek. In April 1965, a dispute there contributed to the Indo-Pakistani War of 1965, when fighting broke out between India and Pakistan. Later the same year, British Prime Minister Harold Wilson successfully persuaded both countries to end hostilities and set up a tribunal, to resolve the dispute. A verdict was reached in 1968 which saw Pakistan getting 10% of its claim of . The majority of the area thus remained with India. Tensions spurted again in 1999 during the Atlantique Incident.
The Rann is also famous for the Indian Wild Ass sanctuary, the Little Rann of Kutch, where the last of three species of Asiatic Wild Ass (Equus hemionus khur or khar), the only ones in Asia, still exists along with wolves, foxes, jackals, chinkara gazelles, nilgai antelope and blackbucks. The Rann of Kutch is also the only place in Pakistan and India which plays host to migrating flamingoes. There are 13 species of lark in the Rann of Kutch.