The Indus River is a major river which flows through Pakistan. It also has courses through China and India. Originating in the Tibetan plateau in the vicinity of Lake Mansarovar, the river runs a course through the Ladakh region of Jammu and Kashmir, Gilgit, Baltistan and flows through Pakistan in a southerly direction along the entire length of Pakistan to merge into the Arabian Sea near the port city of Karachi in Sindh. The total length of the river is 3,180 km (1,980 mi). It is Pakistan's longest river.
The river has a total drainage area exceeding 1,165,000 km2 (450,000 sq mi). Its estimated annual flow stands at around 207 km3 (50 cu mi), making it the twenty-first largest river in the world in terms of annual flow. Zanskar is its left bank tributary in Ladakh. In the plains, its left bank tributary is Chenab which itself has four major tributaries, namely, Jhelum, Ravi, Beas and Satluj. Its principal right bank tributaries Shyok, Gilgit, Kabul, Gomal and Kurram. Beginning at the heights of the world in a spring and fed with glaciers and rivers in the Himalayas, the river feeds the ecosystem of temperate forests, plains and arid countryside.
The Indus forms the delta of Pakistan mentioned in the Vedic Rig Veda as Sapta Sindhu and the Iranic Zend Avesta as Hapta Hindu (both sets of terms meaning Seven Rivers). The river has been a source of wonder during the Classical Period. King Darius of Persia sent Scylax of Caryanda to explore the river in 510 BCE.
Information based on http://en.wikipedia.org/wiki/Indus_valley