Egypt was a Christian country before the 7th century, and after Islam arrived, the country was gradually Islamised into a majority-Muslim country. It is not known when Muslims reached a majority variously estimated from c. 1000 CE to as late as the 14th century. Egypt emerged as a centre of politics and culture in the Muslim world. Under Anwar Sadat, Islam became the official state religion and Sharia the main source of law. It is estimated that 15 million Egyptians follow Native Sufi orders, with the Sufi leadership asserting that the numbers are much greater as many Egyptian Sufis are not officially registered with a Sufi order. At least 305 people were killed during a November 2017 attack on a Sufi mosque in Sinai.