Arab commanders have treated non-Arab (notably Berber) auxiliaries inconsistently, and often rather shabbily, from the early days of Muslim conquest of North Africa.

Berbers had undertaken much of the fighting in the conquest in Spain, but they had received a lesser share of the spoils and had been frequently assigned to the harsher duties (e.g., Berbers are thrown into the vanguard while Arab forces are kept in the back; they are 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, have treated their Berber forces particularly poorly.

Most grievously, Arab governors continue to levy extraordinary dhimmi taxation (the jizyah and kharaj) and slave-tributes on non-Arab populations that have converted to Islam, in direct contravention of Islamic law.

This had become particularly routine during the caliphates of Walid I and Sulayman.

The Umayyad caliph Umar II finally forbade the levying of extraordinary taxation and slave tributes from non-Arab Muslims in 718, defusing much of the tension.

But expensive military reverses in the 720s and 730s have forced caliphal authorities to look for innovative ways to replenish their treasuries.

During the caliphate of Hisham from 724, the prohibitions had been sidestepped with reinterpretations (e.g.

tying the kharaj land tax to the land rather than the owner, so that lands that were at any point subject to the kharaj remained under kharaj even if currently owned by a Muslim.)

As a result, resentful Berbers had grown receptive to radical Kharijite activists from the east (notably of Sufrite and later Ibadite persuasion) which had begun arriving in the Maghreb in the 720s.

The Kharijites preach a puritan form of Islam, promising a new political order, where all Muslims will be equal, irrespective of ethnicity or tribal status, and Islamic law will be strictly adhered to.

The appeal of the Kharijite message to Berber ears has allowed their activists to gradually penetrate Berber regiments and population centers.

Sporadic mutinies by Berber garrisons (e.g.

under Munnus in Cerdanya, Spain, in 729-31) have been put down with difficulty.

One Ifriqiyan governor, Yazid ibn Abi Muslim, who had openly resumed the jizya and humiliated his Berber guard by branding their hands, had been assassinated in 721.

Ubayd Allah ibn al-Habhab had been appointed Umayyad governor in Kairouan in 734 with supervisory authority over all the Maghreb (North Africa) and al-Andalus (Spain).

Coming in after a period of mismanagement, Ubayd Allah had soon set about expanding the fiscal resources of the government by leaning heavily on the non-Arab populations, resuming the extraordinary taxation and slave-tribute without apologies.

His deputies Oqba ibn al-Hajjaj al-Saluli in Córdoba (Spain) and Omar ibn el-Moradi in Tangier (Morocco) have been given similar instructions.

The failure of expensive expeditions into Gaul during the period 732-737, repulsed by the Franks under Charles Martel, has only increased the tax burden.

The parallel failure of the caliphal armies in the east brings no fiscal relief from Damascus.