The name is Iranic in its origin and etymologically identical to those of the Little Zab and Great Zab rivers in Iraq and the Pamirs.
The two principal drainage channels of the Zhob district are the Zhob River and the Kundar River, both flow into the Gomal River. The general direction of the rivers is from southwest to northeast. The Zhob River rises at Tsari Mehtarazai pass, the watershed a distance of about 400 kilometres. The broad plain of the Zhob River is occupied by the alluvial formation. The Kundar River rises from the central and highest point of the TobaKakar range, a few kilometres northeast of the Sakir. It constitutes boundary between Pakistan and Afghanistan territory for a considerable length. The other subsidiary rivers or streams include the Baskan, Chukhan, Sri Toi, Sawar, and Surab.