Description　　The Cholistan desert, or Rohi, is the western part of the Thar desert of the sub-continent which lies in modern Pakistan. There is archaeological evidence that this area was once watered

Description

　　The Cholistan desert, or Rohi, is the western part of the Thar desert of the sub-continent which lies in modern Pakistan. There is archaeological evidence that this area was once watered by the Hakra river and was home to an Indus Valley culture based on agriculture. This river, the bed of which can be seen clearly etched into the desert landscape, supported settlements from ca. 4000 BC until around 600 B.C. when the river changed its flow and subsequently vanished underground. Since then the Cholistan area has been a stark and inhospitable desert environment at the edge of empires.

　　The medieval forts of the Cholistan desert landscape are a group of up to a dozen structures, some standing and some deteriorated. Derawar fort is the best surviving example of this series of historic forts, some dating from pre-Mughal times, but all restored and expanded from the 16th to 18th century by powerful local clans. Other forts include (roughly from north to south) Meergarh, Jaangarh, Marotgarh, Maujgarh, Dingarh, Khangarh, Khairgarh, Bijnotgarh and Islamgarh.These structures form a network across the desert landscape. They served to protect and enable the desert caravan routes; mercantile routes from central Asia to the heartland of the sub-continent and pilgrimage routes between Mecca and India.

　　Derawar fort was built in the 9th c. by Rai Jajja Bhatti. a Rajput ruler of Bhatti clan. The fort was taken over by the Nawab of Bahawalpur, Sadeq Mohammad Khan I, in 1733 They in turn lost control of the fort in 1747 but took the stronghold back in 1804 and it remained as the desert abode of the Nawabs of Bahawalpur until the 1970s. The fort survived intact due to this constant occupation where many of the others built as part of the medieval desert defence have perished.

　　The fort is a massive and visually stunning square structure built of clay bricks. The walls have a length of 1500 meters and stand up to thirty meters high. There are forty circular bastions, ten on each side, which stand 30 m high and are visible across the desert for many miles. Each is decorated with intricate patterns in cut brick work. There are remains of structures inside the fort, may richly decorated with tile and fresco work; the Moti or Pearl Mosque stands nearby and the cemetery of the Nawabs of Bahawalpur filled with ornate and elaborate graves.

　　Derawar and the other forts illustrate the variety of the forms found from square brick structures with circular corner bastions, to square walls completely faced with semi-circular towers, to rectangular and even hexagonal shaped enclosures with angle bastions and square enclosures within an outer wall with multiple bastions. All of these varied forms date from the 16th to late 18th centuries, although many are renovations of previous buildings from as early as the 9th c. Despite this variation in form, all these forts are clustered within an area of only. 250 km N-S and 100 km E-W to the east of the historic cities of Bahawalpur and Yazman.

　　The explanation for this group of fortifications across the flat sands of the Rohi is presumed to be access to water, protection and control of these important water resources and their relationship to the caravan routes across the desert. Derawar, for example, is located at a critical point in the desert where it is possible to access deep water deposits which are all that remains of the ancient Hakra River. As a result, for many centuries Derawar has been an essential stopping and watering point for all caravans entering the great desert on route to trading entrepots to the east.