It is doubtful whether the ancient Arachotus is to be identified with the Arghandab or with its chief confluent the Tarnak, which joins it on the left 50 km (31 mi) southwest of Kandahar.

[5]Historian Asko Parpola states: "Arghandab [...] descends from a height of nearly four kilometers down to about 700 meters when it joins the Helmand River, which eventually forms shallow lakes."

The Historical and Political Gazetteer of Afghanistan cites the explorations of Major G. Lynch in 1841,[b] according to whom the origin of the Arghandab is 20 to 30 miles north of Sang-e-Masha.

Lynch also described the upper course of the river as being a "mountain torrent, dashing over great granite rocks and about 3 feet deep where fordable".

The Kabul-Kandahar Highway passes this way (another reason for supposing the Tarnak to be Arachotus), and the people live off the road to avoid the onerous duties of hospitality.