In 1432 Abd al-Aziz launched another expedition against Tlemcen and died during the campaign. Under Utman (1435–1488) the Hafsids reached their zenith, as the caravan trade through the Sahara and with Egypt was developed, as well as sea trade with Venice and Aragon. The Bedouins and the cities of the empire became largely independent, leaving the Hafsids in control of only Tunis and Constantine. Uthman conquered Tripolitania in 1458 and appointed a governor in Ouargla in 1463. He led two expeditions in Tlemcen in 1462 and 1466 and made the Zayyanids his vassals, the Wattasid state in Morocco also became a vassal of Uthman and therefore the entire Maghreb was briefly under the rule of the Hafsids. Fall of the Hafsids In the 16th century the Hafsids became increasingly caught up in the power struggle between Spain and the Ottoman Empire-supported Corsairs. The Ottomans conquered Tunis in 1534 and held it for one year, driving out the Hafsid ruler Muley Hassan. A year later the King of Spain and Holy Roman Emperor Charles I and V seized Tunis, drove the Ottomans out and restored Muley Hassan as a Habsburg tributary. Due to the Ottoman threat, the Hafsids were vassals of Spain after 1535. The Ottomans again conquered Tunis in 1569 and held it for four years. Don Juan of Austria recaptured it in 1573. The Ottomans reconquered Tunis in 1574, and Muhammad VI, the last Caliph of the Hafsids, was brought to Constantinople and was subsequently executed due to his collaboration with Spain and the desire of the Ottoman Sultan to take the title of Caliph as he now controlled Mecca and Medina. The Hafsid lineage survived the Ottoman massacre by a branch of the family being taken to the Canary Island of Tenerife by the Spanish. Economy The Hafsids, with their location in Ifriqiya, was rich in agriculture and trade. Instead of placing the capital at inland cities such as Kairouan, Tunis was chosen as the capital due to its position on the coast as a port linking the Western and Eastern Mediterranean. Christian merchants from Europe were given their own enclaves in various cities on the Mediterranean coast, promoting trans-Mediterranean trade. Under the Hafsids, commerce and diplomatic relations with Christian Europe grew significantly, however piracy against Christian shipping grew as well, particularly during the rule of Abd al-Aziz II (1394–1434). By the mid-14th century, the population of Tunis