The Kabul River (, , ), the classical Cophen , is a river that emerges in the Sanglakh Range of the Hindu Kush mountains in the northeastern part of Maidan Wardak Province, Afghanistan. It is separated from the watershed of the Helmand River by the Unai Pass. The Kabul River empties into the Indus River near Attock, Pakistan. It is the main river in eastern Afghanistan and the Khyber Pakhtunkhwa province of Pakistan. Course The Kabul River, which measures long, passes through the cities of Kabul and Jalalabad in Afghanistan. Its large drainage basin covers the eastern provinces of Nangarhār, Kunar, Laḡmān, Lōgar, Kabul, Kāpisā, Parvān, Panjšēr, and Bāmiān before it flows into Khyber Pakhtunkhwa in Pakistan some north of the Durand Line border crossing at Torkham. In Khyber Pakhtunkhwa, the river passes through the cities of Peshawar, Charsadda, and Nowshera. A majority of the Kabul River’s water originates from the snow and glaciers of Chitral District, out of which it flows into Afghanistan. In its upper reaches it is known as the Sarchashma. The major tributaries of the Kabul River are the Logar, Panjshir, Alingar, Surkhab, Kunar, Bara, and Swat rivers. Hydrology The Kabul River is little more than a trickle for most of the year, but swells in summer due to melting snows in the Hindu Kush Range. Its largest tributary is the Kunar River, which starts out as the Mastuj River, flowing from the Chiantar glacie in Brughil valley in Chitral, Pakistan and after flowing south into Afghanistan it is met by the Bashgal river flowing from Nurestan. The Kunar meets the Kabul near Jalalabad. In spite of the Kunar carrying more water than the Kabul, the river continues as the Kabul River after this confluence, mainly for the political and historical significance of the name. Dams The Kabul River is impounded by several dams that were constructed in the 20th century. Three dams are located in the Kabul and Nangarhar provinces of Afghanistan, including the Surobi dam, a hydroelectric source for Kabul constructed 1957 with assistance by Germany, the Naghlu dam, which was later built by Soviet scientists in the 1960s, and the Darunta dam. The Warsak Dam is also in the Valley of Peshawar in Pakistan, approximately 20 km northwest of the city of Peshawar. History Expedition of Alexander the Great into Asia In Arrian's The Campaigns of Alexander, the River Kabul is referred to