Hinduism is the second most prevalent religion and predates Buddhism. Islam is the third most prevalent religion in the country, having first been brought to the island by Arab traders over the course of many centuries, starting around the 7th century CE. Most Muslims are Sunni who follow the Shafi'i school. Most followers today are believed to be descendants of those Arab traders and the local women they married. Christianity reached the country through Western colonists in the early 16th century. Around 7.4% of the Sri Lankan population are Christians, of whom 82% are Roman Catholics who trace their religious heritage directly to the Portuguese. Tamil Catholics attribute their religious heritage to St. Francis Xavier as well as Portuguese missionaries. The remaining Christians are evenly split between the Anglican Church of Ceylon and other Protestant denominations. There is also a small population of Zoroastrian immigrants from India (Parsis) who settled in Ceylon during the period of British rule, but this community has steadily dwindled in recent years.