Shortly after the end of the Arab conquest of the Maghreb at the beginning of the 8th century, the Berber revolt of 740 broke out, led by indigenous tribes in contestation of the fiscal policy and the slave trade practised by the representatives of the Umayyads of Damascus. The revolts supported the Kharijite movement, that preached equality of the faithful within the community, and advocated insurrection against an unjust power by the toleration of open access to the imamate (imam is used by the Kharijites in the sense of supreme spiritual guide of the community of the faithful). Following the revolt, several autonomous Kharijite powers formed in the Maghreb, in particular the Barghawata in the Tamesna (Morocco’s Atlantic plains), the Midrarids of Sijilmassa and the Rustamids of Tahert (or Tahart, modern-day Tiaret).
The eponymous founder of the dynasty, ‘Abd al-Rahmân ibn Rustam, probably of Persian origin, was the leader of the Ibadi tribes (Ibadism being the most widespread Kharijite doctrine) that retreated towards Tahert in 761, where they founded their capital city. In 777, ‘Abd al-Rahmân was styled “Manifest Imam”; he was to be the ancestor of a dynasty that would reign over a large part of the central Maghreb until the arrival of the Fatimids. Contrary to the principle of the freedom of the faithful to choose an imam, professed by the Kharijites, ‘Abd al-Rahmân ibn Rustam’s successors set up an hereditary dynastic power. This caused extensive political and religious dissension that weakened the Rustamid power. Thus, with the accession of ‘Abd al-Wahhâb, son of the founder of the dynasty, in 784, some Ibadites refused to recognise his legitimacy, revolted and formed the Nukkarite movement, one of the main sects of Ibadism in the Maghreb.
It is difficult to define precisely the territorial limits of the Rustamid power. Its authority was recognized, nominally at least, by several predominantly Ibadite regions, (notably in Tripolitania or in the Djerid), but only extended very partially into the western part of the central Maghreb (the modern Algerian west), where it co-existed with several autonomous Alid principalities. Largely unstructured, the Rustamid power doesn’t seem to have given rise to a developed administrative machinery and remained strongly tribal in its workings. The Rustamid’ power base drew mainly on two tribal groups, the Nafusa, who formed the backbone of the army, and the Mazâta nomads, affluent thanks to their involvement in Trans-Saharan trade. Thus the second Rustamid imam, ‘Abd al-Wahhâb, stated that the Ibadite power rested upon “the swords of the Nafusa and the wealth of the Mazata”. The Rustamids do not seem to have struck any coin, unlike the majority of the Muslim powers of the Maghreb.
Tahert was the dynasty’s capital and main urban centre. The Rustamid settlement, New Tahert, is situated close to an ancient locality, Old Tahert according to Arabic sources, that had a citadel and a double rampart, probably dating from the Byzantine period. The Rustamids’ new town, situated on a plateau, is reputed to have been built on the ruins of another ancient site, and this may explain the toponym Tagdemt (the Berber form of the Arabic qadîm, “ancient”), which also referred to it since the Middle Ages.
Crossed as it was by two waterways, New Tahert had sufficient hydraulic resources for the development of prosperous orchards and market gardening. Hydraulic planning work enabled optimum use of this water: and now the ruins of an hydraulic building consisting of a series of basins have been discovered, tying in with the Arabic sources that describe mills driven by the force of the water.
The planning of Tahert is characterised in its fragmented appearance. The town is made up of adjoining districts, based on community (inhabitants originating from Kairouan, Kufa or Basra) or tribe (the Nafusa Berbers). A strong indigenous Christian community (‘ajam or barqajâna in the Arabic texts) lived in Tahert, where it had a church and a market.
A citadel towered over Tahert, called “the impregnable Casbah” by the geographer al-Bakri. Georges Marçais situated it in the south-west corner of the city. It was a rectangular building, with a single direct entrance leading into a large central courtyard, surrounded on four sides by rooms of varying sizes, including living quarters, stables and shops. The defensive function of the Casbah accounts for its sobriety; but this absence of all decoration is also explained by the Rustamid imams’ conspicuous austerity and their puritan ideology, as embodied in the great mosque, known to us only through written indications. Al-Bakri speaks of a building with four naves, whose vaults were held up by wooden columns. The archaeological material discovered during ancient excavations carried out in Tahert consists mainly of turned ceramic with a distinctive and most characteristic excised decoration. The walls of the vases are adorned with geometric motifs, mostly triangular, but also linear or curved.
Having a territory that was largely landlocked, the Rustamids only had limited dealings with the Mediterranean world. Thanks to Andalusian sources, we know that they maintained relations with the Cordoban Umeyyads, both dynasties being opposed to the Aghlabids, who had remained faithful to the Abbassids.
On the other hand Tahert had become a major Trans-Saharan trading post: through it passed supplies of gold dust and African slaves en route for the Maghreb and Mediterranean market. In its dealings with Black Africa, it was also a major centre for the dissemination of Islam, whose teachings were transported by the Ibadite merchants and missionaries. Tahert was also involved in trade with other parts of the Muslim world: it had a Radhanite market, the Rahâdina being multilingual Jewish merchants who had built up a trade-network with activities ranging from China, India or Transoxiana to the Maghreb, Al-Andalus and the Kingdom of the Franks.
In 909, after their victory over the Aghlabids in Ifriqiya, the Fatimid armies overran Tahert, put the last imam, al-Yaqzan (906-909), and his family to death, and devastated the town. Then the Ibadites of Tahert took refuge in Sedrata, near Ouargla, in the Algerian desert. The ruins of Sedrata, dating from the tenth to eleevnth centuries, are known thanks to ancient excavations. They constitue the legacy of Rastamid art and architecture. Thus a mosque covered with adjoining oval domes and several residential blocks have been uncovered. The art of Sedrata is characterized above all by its plaster decoration, using geometric or floral motifs of simple workmanship, or again Kufic inscriptions.
The Ibadites’ presence in Sédrata was relatively brief. Around 1077, the end of a new migratory phase saw them settle in the Mzab, which has remained to this day a veritable bastion of Maghrebin Ibadism.