 By the middle of the 1st century BC, the Kushans' base of control became Afghanistan and their empire spanned from the north of the Pamir mountains to the Ganges river valley in India.Early in the 2nd century under Kanishka, the most powerful of the Kushan rulers, the empire reached its greatest geographic and cultural breadth to become a center of literature and art.Kanishka extended Kushan control to the mouth of the Indus River on the Arabian Sea, into Kashmir, and into what is today the Chinese-controlled area north of Tibet.