 The Umayyads ultimately triumphed and established a caliphate that had reached the Indian Subcontinent by the early 8th century.A Tayyid commander named al-Qasim ibn Tha'laba ibn Abdullah ibn Hasn played an instrumental role in the Umayyad conquest of Sindh in 712 by killing the country's Hindu king Raja Dahir in battle.The Abbasids contested leadership of the caliphate and overtook the Umayyads in what became known as the Abbasid Revolution in the mid-8th century.