who still held on in the northern highland. It was mainly because of the victories which he scored over his rivals that he assumed the honorific title al-Muzaffar (the victorious). After the fall of Baghdad to the Mongols in 1258, al-Muzaffar Yusuf I appropriated the title of caliph. He chose the city of Ta'izz to become the political capital of the kingdom because of its strategic location and proximity to Aden. Al-Muzaffar Yusuf I died in 1296 having reigned for 47 years. When the news of his death reached the Zaydi imam Al-Mutawakkil al-Mutahhar bin Yahya he commented by saying: The Rasulid state nurtured Yemen's commercial links with India and the Far East. They profited greatly by the Red Sea transit trade via Aden and Zabid. The economy also boomed due to the agricultural development programs instituted by the kings who promoted massive cultivation of palms. It was during this period that coffee became a lucrative cash crop in Yemen. The Rasulid kings enjoyed the support of the population of Tihama and southern Yemen while they had to buy the loyalty of Yemen's restive northern highland tribes. The Rasulid sultans built numerous Madrasas in order to solidify the Shafi'i school of thought which is still the dominant school of jurisprudence amongst Yemenis today. Under their rule, Ta'izz and Zabid became major international centers of Islamic learning. The Kings themselves were learned men in their own right who not only had important libraries but who also wrote treatises on a wide array of subjects, ranging from astrology and medicine to agriculture and genealogy. The dynasty is regarded as the greatest native Yemeni state since the fall of pre-Islamic Himyarite Kingdom. They were, of course, of Turkic descent but claimed an ancient Yemenite origin to justify their rule. The Rasulids were not the first dynasty to create a fictitious genealogy for political purposes, nor were they doing anything out of the ordinary in the tribal context of Arabia. By claiming descent from a solid Yemenite tribe, the Rasulid brought Yemen to a vital sense of unity in an otherwise chaotic regional milieu. They had a difficult relationship with the Mamluks of Egypt because the latter considered them a vassal state. Their competition centered over the Hejaz and the right to provide kiswa of the Ka'aba in Mecca. The dynasty became increasingly threatened by disgruntled family members over the problem of succession, combined