Islam spread peacefully throughout India over many centuries through trade and Sufi mystics, not by force or violence. Arab traders introduced Islam to coastal regions in the 7th century. While some areas came under Muslim political rule in the 8th century, local religions and social structures were left intact. People often converted to Islam in whole castes to escape the oppression and lack of social mobility within the caste system. Islam appealed for its message of equality. By the time Muslim rule ended in many areas, Islam had become deeply integrated into Indian society.