The last Prophet of Islam, Prophet Muhammad (SAW), completely changed the intellectual outlook of Arabia. Within a span of 23 years he transformed the barbarous and impious Arabs into a civilized and religious nation. During his life and also after his death, Muslims took the message of Islam to every corner of the world and within a few years Muslims became the super power of the era.
Trade relations between Arabia and the Sub-continent dated back to ancient times. Long before the advent of Islam in Arabia, the Arabs used to visit the coast of Southern India, which then provided the link between the ports of South and South East Asia. After the Arab traders became Muslim, they brought Islam to South Asia. A number of local Indians living in the coastal areas embraced Islam. However, it was the Muslim conquests in Persia, including the provinces of Kirman and Makran, which brought the Arabs face to face with the then ruler of Sindh, who had allied with the ruler of Makran against the Muslims. But, it was not until the sea borne trade of the Arabs in the Indian Ocean was jeopardized that serious attempts were made to subjugate Sindh.
During the reign of the great Umayyad Caliph Walid bin Abdul Malik, Hajjaj bin Yousaf was appointed as the governor of the Eastern Provinces. At that time, Raja Dahir, a Brahman, ruled Sindh. However, the majority of the people living in the region were Shudders or Buddhists. Dahir treated members of these denominations inhumanly. They were not allowed to ride horses or to wear a turban or shoes. Sindhi pirates, protected by Dahir, were active on the coastal areas and whenever they got a chance, they plundered the ships passing by Daibul.