The Inus River {Hindi and Sanskrit: सिन्धु Sindhu; Urdu: سندھ Sindh; Sindhi: سنڌو Sindhu; Punjabi (Shahmukhi: سندھ, Gurmukhi: ਸਿੰਧੂ) Sindhu; Persian: Hinduحندو ; Pashto: Abasin ّآباسن"Father of Rivers"; Tibetan: Sengge Chu "Lion River"; Chinese: 印度 Yìndù; Greek: Ινδός Indos} is the longest and most important river and often considered the life-line of Pakistan. It is the longest river and the third largest river, in terms of annual flow, in the Indian subcontinent. The British used the name "India" for the entire subcontinent based on the appellation of this river. Originating in the Tibetan plateau in the vicinity of Lake Mansarovar, the river runs a course through Ladakh district of Jammu and Kashmir and Northern Areas, flowing through the North in a southerly direction along the entire length of the country, to merge into the Arabian Sea near Pakistan's port city Karachi. The total length of the river is 3,180 kilometres (1,976 miles). The river has a total drainage area exceeding 1,165,000 square kilometres (450,000 square miles). The river's estimated annual flow stands at around 207 cubic kilometres. Beginning at the heights of the world with glaciers, the river feeds the ecosystem of temperate forests, plains and arid countryside. Together with the rivers Chenab, Ravi, Sutlej, Jhelum, Beas and the extinct Sarasvati River, the Indus forms the Sapta Sindhu ("Seven Rivers") delta in the Sindh province of Pakistan. It has 20 major tributaries.