Bahawalpur (Bhawalpur, Bhawulpore) is a city in Punjab, Pakistan. You need a guide to take you to Derawar, and also permission from the present Amir of Bahawalpur to get inside the fort. The drive takes three to four hours through fasinating barren landscape. The cholistan desert covers 26,000 sq km (10,000 sq miles) and extends into the Thar desert to India. The whole area was once well watered by the river Ghaggar, now called the Hakara in Pakistan, and known in vedic times as the Sarasvati. All along the 500 km (300 miles) of the dried-up river are over 400 archaeological sites. Most of these date from the indus civilisation, 45,00 years ago, and are clustered round Derawar Fort, the only perennial water hole in the desert. There is very little to make out today.The desert has an average rainfall of 12 cm (5 inches) a year, and there is very little civilisation. The underground water is brackish. The few people of the desert dig artificial wells in the troughs between the sand hills and use camels to draw the water up.