William Blandford reported the presence of flint cores and flakes in the hills near Sukkur and Rohri on the Indus River in 1880. In 1939, the geologists De Terra and Paterson suggested that some of the flint tools resembled those found in Mohenjo-daro.
More recent excavations were carried out by Bridget Allchin in 1975-76. She discovered several Paleolithic and Harappan sites (from 100,000 to 2,500 B.C.E.) located mainly at the northern and southwestern ends of the sprawling hills.
Excavations at Mohenjo-daro have shown that the flint used by ancient Indus communities was not available from the silty-clay plain of the Indus river. It was imported from elsewhere. The probable source was the Rohri Hills, close to the pre-historic site of Kot Diji, and 50 kilometers to the north-east of Mohenjo-daro.
From 1995-1997 the first Acheulian workshops were excavated. Named after remains first found in France, the Acheulians date to 50,000 B.C.E. The size of the Rohri quarries suggests that early humans worked in large entities long before the Indus cities of 2500 B.C.E.
The Rohri Hills are a limestone plateau (map), 40 km long and 16 km wide, deeply dissected by erosion. They are surrounded on three sides by the alluvial plain of the Indus river.
On the eastern side they are separated from the Thar Desert by the Nara Canal which flows in an old bed of the Indus River. The region is currently a steeped desert, or an arid subtropical lowland. It is one of the hottest parts of the world. The temperature is 46 Celcius in June, and rainfall minimal at 90 to 125 nn per year.
About 2,000 early and late Paleolithic and Harappan sites have been discovered in the area during four surveys in 1986, and 1993-97. Most are concentrated around the shrine of Shadee Shaheed. They consist of quarries, workshops and chipping floors related to the mining and manufacture of flint artifacts.
Various structures were observed, including deep pits now filled with wind-blown sand. Chipping floors and huge heaps of artifacts, some even 10 meters long by 5 wide and nearly half a meter thick were found. Some were extremely rich in subconical long cores, narrow bladlets and various kinds of waste flint from manufacturing processes. Pieces of typical Harappan painted pottery were also collected from these structures.