The Indus valley civilization is the farthest visible outpost of archeology in the abyss of prehistoric times. The areas constituting Pakistan have had a historical individuality of their own and Sindh is the most important among such areas.
The earliest authentic history of Sindh dates from the time when Alexander the Great abandoned his scheme of conquest towards the Ganges, alarmed at the discontent of his soldiers. He embarked a portion of the army in boats, floated them down the Jhelum and the Chenab, and marched the remainder on the banks of the river till he came to the Indus.
The Arab conquest of Sindh by Muhammad Bin Qasim in 712 AD gave the Muslims a firm foothold on the sub-continent. Khalifa Harun-al-Rashid (786-809 AD) was able to extend the frontiers of Sindh on its western side. For nearly two hundred years since its conquest by Muhammad Bin Qasim, Sindh remained an integral part of the Umayyad and the Abbasid caliphates. The provincial governors were appointed directly by the central government. History has preserved a record of some 37 of them.