Umayyad interest in Sindh

According to Wink, Umayyad interest in the region was galvanized by the operation of the Meds (a tribe of Scythians living in Sindh) and others.^[12] The Meds had engaged in piracy on Sassanid shipping in the past, from the mouth of the Tigris to the Sri Lankan coast, in their bawarij and now were able to prey on Arab shipping from their bases at Kutch, Debal and Kathiawar.^[12] At the time, Sindh was the wild frontier region of al-Hind, inhabited mostly by semi-nomadic tribes whose activities disturbed much of the Western Indian Ocean.^[12] Muslim sources insist that it was these persistent activities along increasingly important Indian trade routes by Debal pirates and others which forced the Arabs to subjugate the area, in order to control the seaports and maritime routes of which Sindh was the nucleus, as well as, the overland passage.^[13] During Hajjaj's governorship, the Meds of Debal in one of their raids had kidnapped Muslim women travelling from Sri Lanka to Arabia, thus providing a casus belli to the rising power of the Umayyad Caliphate that enabled them to gain a foothold in the Makran, Balochistan and Sindh regions.^[12][14][15]

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Also cited as a reason for this campaign was the policy of providing refuge to Sassanids fleeing the Arab advance and to Arab rebels from the Umayyad consolidation of their rule.^{[clarification needed]}
These Arabs were imprisoned later on by the Governor Deebal Partaab Raye. A letter written by an Arab girl named Nahed who escaped from the prison of Partab Raye asked Hajjaj Bin Yusuf for help. When Hajjaj asked Dahir for the release of prisoners and compensation, the latter refused on the ground that he had no control over those. Al-Hajjaj sent Muhammad Bin Qasim for action against the Sindh in 711.^{[citation needed]}
The mawali; new non-Arab converts; who were usually allied with Al-Hajjaj's political opponents and thus were frequently forced to participate in battles on the frontier of the Umayyad Caliphate — such as Kabul, Sindh and Transoxania.^[16] An actual push into the region had been out of favor as an Arab policy since the time of the Rashidun Caliph Umar bin Khattab, who upon receipt of reports of it being an inhospitable and poor land, had stopped further expeditionary ventures into the region