The majority religion in Vietnam is Buddhism, with an estimated 75% of the population identifying as Buddhist. Buddhism was introduced to Vietnam from China in the first century AD and over time it has become deeply ingrained in Vietnamese culture and society. Other major religions in Vietnam include Catholicism (7%), Protestantism (1.5%), Hoa Hao Buddhism (1.5%), Cao Dai (1%), and Islam (0.5%). There is also a small animist minority, which is the belief in spirits and the power of nature. Religious freedom is guaranteed by the Constitution of Vietnam, although some religious groups face restrictions and discrimination.