The Rasulid sultans built numerous Madrasas to solidify the Shafi'i school of thought, which is still the dominant school of jurisprudence amongst Yemenis today. Under their rule, Taiz and Zabid became major international centres of Islamic learning. The kings themselves were educated men in their own right, who not only had important libraries but also wrote treatises on a wide array of subjects, ranging from astrology and medicine to agriculture and genealogy.