Despite their relatively short tenure, the Ayyubid dynasty had a transformative effect on the region, particularly Egypt. Under the Ayyubids, Egypt, which had previously been a formally Shi'a caliphate, became the dominant Sunni political and military force, and the economic and cultural centre of the region, a status that it would retain until it was conquered by the Ottomans in 1517. Throughout the sultanate, Ayyubid rule ushered in an era of economic prosperity, and the facilities and patronage provided by the Ayyubids led to a resurgence in intellectual activity in the Islamic world. This period was also marked by an Ayyubid process of vigorously strengthening Sunni Muslim dominance in the region by constructing numerous madrasas (Islamic schools of law) in their major cities. Even after being toppled by the Mamluk Sultanate, the sultanate built by Saladin and the Ayyubids would continue in Egypt, the Levant and the Hijaz for another 267 years.