wheat, cotton, millet, and rice grown in the surrounding region. Dates and mangoes are also grown here. Canals supply water for irrigation. The principal industries are cotton ginning, rice and flour milling, and the handweaving of textiles. Cholistan Desert East of Bahawalpur is the Cholistan Desert which covers about an area of 20,000 km 2 of Bahawalpur and 1000 km² of Rahim Yar Khan and extends into the Thar Desert of India. The region was once watered by the Hakra River. At one time there were 400 forts in the area and archaeological finds around the Derawar Fort, the only place with a perennial waterhole, indicate that it was contemporaneous with the Indus Valley Civilisation. The average annual rainfall is only 12 cm, and the little cultivation that exists is made possible by underground wells, drawn up by the camels. The water is stored in troughs, built by the tribes, between sandhills and din waterholes called tobas. The forts here were built at 29 km intervals, which probably served as guard posts for the camel caravan routes. There were three rows of these forts. The first line of forts began from Phulra and went to Lera, the second from Rukhanpur to Islamgarh, and the third from Bilcaner to Kapoo. They are all in ruins now, and you can see that they were built with double walls of gypsum blocks and mud. Some of them date back to 1000 BCE, and were destroyed and rebuilt many times. Administration The district is administratively divided into five tehsils and 107 Union Councils: Demographics At the time of the 2017 census the district had a population of 3,669,176, of which 1,879,702 were males and 1,789,148 females. Rural population is 2,497,014 while the urban population is 1,172,162. The literacy rate was 50.27%. Languages At the time of the 2017 Census of Pakistan, the distribution of the population of Bahawalpur District by first language was as follows: 67.1% Saraiki 25.1% Punjabi 5.7% Urdu 0.6% Pashto 0.4% Hindko 0.2% Sindhi 0.1% Balochi 0.1% Brahui 0.0% Kashmiri 0.8% Others Religion Muslims were the predominant religious community with 98.34% of the population while Hindus (including Scheduled Castes) were 1.12% of the population. Transportation Buses run daily between Bahawalpur and other major cities of Pakistan. Pakistan's longest national highway, N-5, also passes through town, connecting Bahawalpur to Karachi and Lahore. Economy The main crops for which Bahawalpur is recognized are