The river was also known as Arjikuja of the Vedas, or Vipasa to the ancient Indians, and the Hyphasis to the Ancient Greeks.
It is said that Beas is a misnomer for Vayasa (exchange of B with V and always truncation of the last vowel is common in North Indian languages) and is named after Veda Vyasa, the presiding patron of the river; he is said to have created it from its source lake, the Vyas Kund.
The Beas River marks the eastern-most border of Alexander's conquests in 326 BC. It was also one of the rivers which created problem in Alexander's invasion towards India. His troops mutinied here in 326 BCE, refusing to go any further; they had been away from home for eight years. Alexander shut himself in his tent for three days, but when his men did not change their desires he gave in, raising twelve colossal altars to mark the limit and glory of his expedition. According to the Kavyamimansa  of Rajasekhara, the kingdom-territories of the Gurjara-Pratihara monarch Mahipala I extended as far as the upper course of the river Beas in the north-west.
In the 20th Century, the river was developed under the Beas Project for irrigation and hydroelectric power generation purposes. The second-phase Pong Dam was completed in 1974 followed by the first-phase 140 km (87 mi) upstream, Pandoh Dam in 1977. The Pong Dam served initially to primarily provide irrigation below Talwara but was soon developed as well for power generation; its power station has a 360 MW installed capacity. The Pandoh Dam diverts the river through a system of tunnels and channels to the 990 MW Dehar Power Station on the Sutlej River, connecting both rivers.
The river rises on the southern face of Rohtang Pass in Kullu 13,326 feet above the sea-level, from the Beas Kund lake. It traverses the Mandi District and enters Kangra District at Sanghol, 1,920 feet above sea-level. During its lower hill course the Beas is crossed by numerous ferries, at many of which the mean of communication consist of inflated skins (darais). Near Reh in Kangra District it divides into three channels, which reunites after passing Mirthal, 1,000 feet above sea-level. On meeting the Sivalik Hills in Hoshiarpur, the river sweeps sharply northward forming boundary between that district and Kangra District. Then bending round the base of Sivalik Hills, it takes the southerly direction separating the district of Gurdaspur and Hoshiapur. After touching the Jullundur district for a few miles the river forms the boundary between Amritsar and Kapurthala district. Finally the Beas joins the river Satulej at the south-western boundary of Kapurthala district of Punjab after a total course of 290 miles. The chief tributaries are Bain, Banganga, Luni and Uhal. The Sutlej continues into Pakistani Punjab and joins the Chenab River at Uch near Bahawalpur to form the Panjnad River; the latter in turn joins the Indus River at Mithankot. The waters of the Beas and Sutlej rivers are allocated to India under the Indus Waters Treaty between India and Pakistan.