At the beginning of the Caliphate or Islamic Empire, the reliance on courts initially confined sponsorship and scholarly activities to major centres. Within several centuries, the development of Muslim educational institutions such as the madrasah and masjid eventually introduced such activities to provincial towns and dispersed them across the Islamic legal schools and Sufi orders. In addition to religious subjects, they also taught the "rational sciences," as varied as mathematics, astronomy, astrology, geography, alchemy, philosophy, magic, and occultism, depending on the curriculum of the specific institution in question. The madaris, however, were not centres of advanced scientific study; scientific advances in Islam were usually carried out by scholars working under the patronage of royal courts. During this time,[when?] the Caliphate experienced a growth in literacy, having the highest literacy rate of the Middle Ages, comparable to classical Athens' literacy in antiquity but on a much larger scale. The emergence of the maktab and madrasa institutions played a fundamental role in the relatively high literacy rates of the medieval Islamic world.