The mountains extend southward for about from the Mula River in east-central Balochistan to Cape Monze on the Arabian Sea. In total, the Kirthars cover an area of about 9,000 square kilometers. The Khasa Hills and Mulri Hills close to the Arabian Sea coast are sub-ranges of the Kirthar Mountains which extend into the city limits of Karachi. The mountains are drained by the Gaj River and Hub River.