Kohlu is situated at the southern end of the Sulaimán range and consist chiefly of narrow parallel ridges of closely packed hills which form the gradual descent from the Sulaimán plateau into the plains. They are intersected by numerous hill-torrents and ravines and generally speaking are barren and rugged. The area may be divided into 4 portions: (1) Kohlu; (2) Kahan including Tadri, Daho and Bambor; (3) a portion of Pheawagh, Nesao and Janatali; and (4) Mawand and Gamboli.

The mountain ranges of Kohlu district may be described as presenting a series of limestone ridges, forming more or less parallel valleys; the ranges lie, to the east of 69°E, from north-east to south-west and to the west of that line from north-west to south-east. They include the Dungán (2,091 m), Lakar (2,078 m), Siálu (2,473 m), Tikil or Tikhil (2,099 m), Batur (1,751 m), Jandran (2,050 m), Bibartak (1,916 m), Siah Koh (1,678 m), Kup, Chappar (1,425 m), Sir Ani (1,155 m), Shatrak (1,158 m), Turki Koh, Tatra (1,225 m), Rastráni (914-1,219 m), Danda range including Nafusk (1,145 m), Bambor (1,490 m) and Gurándáni, and Sunari range (1,716-1,750 m). The principal passes in the district are the Bibartak, the Wanga, the Narial, the Mezhliar, the Sinni, the Ormazhi or Bar, the Nári, Kucháli and Spintangi on the Sibi-Harnai road; the Arand between Khajak and Kot Mandai; the Angúr between Gamboli and Sémbar; the Sémbar between Gamboli and Thal; the Pazha between Béji and Thal; the Kuba Wanga between Bála Dháka and Kohlu; the Már between Kohlu and Vitákri; the Luniál between Bor and Kui; the Dojamak on the Kohlu-Kahan road; the Dangar in the Shatrak range; and the Nafusk between the Marri and Bugti areas.

With the exception of the streams of Nesao, Phelawagh and Janatali, which flow to the east, the main direction of the rivers is almost due west. The principal rivers are: Lahri; Bor; Rod Baladhaka; Rod Barg; Béji and Dáda, both of which are affluents of the Nári and have a perennial supply of water; the Talli stream (known as the Sundimari, Chákar Thank, Karmári and Manjra in different localities) which rises in the hills bordering on Kohlu and has an intermittent flow of perennial water; and the Nál, also called the Gandhár, which carries off the drainage of the Makhmar, Suri Kaur and Kahan valleys. It is a fine stream at Tratani but disappears before it reaches Lahri, except during floods.