Indus River

The Indus is a major transboundary river of Asia and the principal waterway of the trans-Himalayan region of South and Central Asia. Rising from springs in the highlands northeast of Mount Kailash in western Tibet, it flows northwest through Ladakh and Gilgit–Baltistan before turning south-by-southwest across Pakistan and ultimately emptying into the Arabian Sea near Karachi. Fed by glaciers and tributary rivers from the Himalayas, Karakoram and Hindu Kush, the Indus supports diverse ecosystems ranging from temperate forests to arid plains and remains vital to the societies and economies that developed along its banks.

Geographic Setting

The river originates in the Tibetan Plateau, near the sacred Mount Kailash, and flows through regions administered by India, Pakistan and China. Its upper course passes through Ladakh, where the Zanskar River joins from the left, and through the deep gorges south of the Nanga Parbat massif. Entering the plains at Kalabagh in Pakistan, the Indus receives major right-bank tributaries including the Shyok, Gilgit, Kabul, Kurram and Gomal rivers. In the Punjab Plain it is joined by the Panjnad River, formed by the confluence of the Jhelum, Chenab, Ravi, Beas and Sutlej rivers. The lower Indus divides into distributaries before forming a large delta south of Thatta in Sindh.
Seasonal variations strongly influence its flow: discharge diminishes in winter and increases dramatically in the monsoon months. The river is unusual in exhibiting a tidal bore near its delta. Geological evidence suggests that its course has shifted over time, including a westward diversion following an early nineteenth-century earthquake.

Length and Drainage

The total length of the Indus varies in published sources, with common figures ranging between roughly 2,900 km and over 3,100 km. A 2011 remeasurement proposed a longer total course beginning at a small lake northeast of Mount Kailash, though full analysis has not yet appeared. Its drainage basin covers an extensive region stretching across Tibet, the Himalayas and the plains of Pakistan, making it one of the world’s major river systems by catchment area and discharge.

Names and Etymology

The name Indus derives from Latin Indus, itself from Greek usage referring both to the river and to the peoples dwelling near it. These forms reflect earlier Old Persian hindu, related to Avestan terms for “river” or “frontier”, all ultimately linked to the Proto-Indo-Iranian root also found in Sanskrit sindhu. In Sanskrit sindhu denotes a stream, river, flood or the region adjacent to the river. Modern names vary across the region: in Urdu the river is called Sindh or Daryā-e Sindh; in Tibetan and Ladakhi Senge Tsangpo; in Balti Gemtsuh; in Pashto Nilab, Sher Darya and Abbasin; and in Sindhi Sindhu, Mehran, Purali and Samundar.

Regional and Economic Importance

Flowing through Ladakh and Gilgit–Baltistan before traversing the plains of Punjab and Sindh, the Indus underpins agriculture, industry and urban life in Pakistan. Punjab—literally “land of five rivers”—relies on the tributaries that ultimately merge into the Indus, and together these waters form the backbone of Pakistan’s irrigated agriculture. The river also supplies potable water and supports major hydroelectric developments such as the Tarbela Dam. Its extensive alluvial plain has shaped settlement patterns for millennia.

Geology

The headwaters of the Indus lie along the Indus–Yarlung suture zone, marking the collision boundary between the Indian and Eurasian plates during the early Eocene. The rising Himalayas deflected both the Indus and the Yarlung Tsangpo, shaping the western and eastern limits of the range respectively. After descending from its Himalayan gorge, the Indus and its tributaries form the fertile Punjab region before entering the low-lying deltaic terrain of Sindh.

Sources and Tributaries

Traditional accounts identify the river’s source at the Sênggê Kanbab (Lion’s Mouth) spring near Mount Kailash. Alternative definitions trace the system farther upstream to the confluence of the Sênggê Zangbo and Gar Tsangpo rivers, or to a small lake proposed in the 2011 remeasurement. Several nearby streams may be longer in absolute length, though many depend on seasonal snowmelt, unlike the perennial Lion’s Mouth spring.
The Zanskar River contributes significant discharge—greater than the Indus itself at their confluence. Major right-bank tributaries reach the river from the Karakoram and Hindu Kush, carrying large volumes of glacial meltwater.

Historical Significance

The Indus Valley, with cities such as Harappa and Mohenjo-daro, hosted one of the world’s earliest urban civilisations, flourishing from around 3300 BCE. Known in Vedic literature as Sapta Sindhu and in Avestan texts as Hapta Hendu, the region held cultural and religious importance in early Indo-Iranian traditions. Later historical polities in the valley included Gandhāra and Sindhu-Sauvīra.
Knowledge of the river reached the classical world when Darius I of Persia sent the Greek explorer Scylax of Caryanda to survey it. The Indus subsequently featured prominently in accounts of the Achaemenid Empire and the campaigns of Alexander the Great.