The early Islamic literature indicates that the conquest of India was one of the very early ambitions of the Muslims, though it was recognized as a particularly difficult one. After conquering Persia, the Arab Umayyad Caliphate incorporated parts of what are now Afghanistan and Pakistan around 720. The book Chach Nama chronicles the Chacha Dynasty's period, following the demise of the Rai Dynasty and the ascent of Chach of Alor to the throne, down to the Arab conquest by Muhammad bin Qasim in the early 8th century AD, by defeating the last Hindu monarch of Sindh, Raja Dahir.

Answer this question, if possible (if impossible, reply "unanswerable"): What empire took over parts of Afghanistan and Pakistan in 720?
Arab Umayyad Caliphate