Although Berbers had undertaken much of the fighting in the Umayyad conquest of Hispania, they were given a lesser share of the spoils and frequently assigned to the harsher duties (e.g. Berbers were thrown into the vanguard while Arab forces were kept in the back; they were assigned garrison duty on the more troubled frontiers). Although the Ifriqiyan Arab governor Musa ibn Nusair had cultivated his Berber lieutenants (most famously, Tariq ibn Ziyad), his successors, notably Yazid ibn Abi Muslim, had treated their Berber forces particularly poorly.