The Indus River Delta (Sindhi: سنڌو ٽِڪور), forms where the Indus River flows into the Arabian Sea in Pakistan. The delta covers an area of about 41,440 km² (16,000 square miles), and is approximately 210 km (130 mi) across where it meets the sea. The active part of the delta is 6,000 km2 in area (2,300 sq mi). The climate is arid, the region only receives between 25 and 50 centimetres (9.8 and 19.7 in) of rainfall in a normal year. The delta is home to the largest arid mangrove forests in the world, as well as many birds, fish and the Indus Dolphin.
Since the 1940s, the delta has received less water as a result of large-scale irrigation works capturing large amounts of the Indus water before it reaches the delta. The result has been catastrophic for both the environment and the local population. As a result, the 2010 Pakistan floods were considered "good news" for the ecosystem and population of the river delta as they brought much needed fresh water.
The population of the active part of the delta was estimated at 900,000 in 2003. Most of the population depends on agriculture and fishing. Mangrove forests provide fuel wood. Many former settlements in the delta have been abandoned as result of lack of water in the Indus and the encroaching Arabian Sea.
According to some accounts, the Macedonian fleet (of Alexander the Great) anchored itself for some time in the Indus river delta. It was damaged by a tsunami generated by an earthquake off the Makran Coast in 325 BC.
According to Tarikh-i-Hind (also known as the Chach Nama) by 6th century A.D. there existed a port called Debal in what is now the western part of the Indus delta. Debal also seemed to be the base of pirates from the tribe of Nagamara. These pirates' raids against the Umayyads, and the refusal to redress the issue by the ruling prince, precipitated the Muslim conquest around 710 AD (by Muhammad bin Qasim). Debal remained a port, and the last recorded mention of it was in 1223 AD. By the time Ibn Batuta reached the Indus delta, Debal had been abandoned due to increased shoaling preventing the then-port from accessing the sea.