After succeeding al-Walid, Sulayman dismissed his predecessor's governors and generals. Many had been handpicked by al-Hajjaj and had led the war efforts which brought the Caliphate to its greatest territorial extent. Among al-Hajjaj's loyalists were the conqueror of Transoxiana (Central Asia), Qutayba ibn Muslim, who was killed by his own troops in an abortive revolt in anticipation of his dismissal, and the conqueror of Sind (the western Indian subcontinent), Muhammad ibn Qasim, who was executed. In the west, Sulayman deposed Musa ibn Nusayr, the conqueror of the Iberian Peninsula (al-Andalus) and governor of Ifriqiya (central North Africa), and had his son Abd al-Aziz, governor of al-Andalus, assassinated. Although he continued his predecessors' militarist policies, expansion largely stopped under Sulayman, partly due to effective resistance along the Central Asian frontiers and the collapse of Arab military leadership and organization there after Qutayba's death. Sulayman's appointee over the eastern Caliphate, his confidant Yazid, invaded the southern Caspian coast in 716, but withdrew and settled for a tributary arrangement after being defeated by the local Iranian rulers. Sulayman intensified the war with the Byzantine Empire, culminating in the 717–718 siege of Constantinople, which ended in an Arab defeat.