The persecution of Christians can be historically traced from the first century of the Christian era to the present day. Christian missionaries and converts to Christianity have both been targeted for persecution, sometimes to the point of being martyred for their faith, ever since the emergence of Christianity. Early Christians were persecuted at the hands of both Jews, from whose religion Christianity arose, and the Romans who controlled many of the early centers of Christianity in the Roman Empire. Since the emergence of Christian states in Late Antiquity, Christians have also been persecuted by other Christians due to differences in doctrine which have been declared heretical. Early in the fourth century, the empire's official persecutions were ended by the Edict of Serdica in 311 and the practice of Christianity legalized by the Edict of Milan in 312. By the year 380, Christians began to persecute each other. The schisms of late antiquity and the Middle Ages – including the Rome–Constantinople schisms and the many Christological controversies – together with the later Protestant Reformation provoked severe conflicts between Christian denominations. During these conflicts, members of the various denominations frequently persecuted each other and engaged in sectarian violence. In the 20th century, Christian populations were persecuted, sometimes, they were persecuted to the point of genocide, by various states, including the Ottoman Empire and its successor state, which committed the Hamidian massacres, the Armenian genocide, the Assyrian genocide, and the Greek genocide, and officially atheist states such as the former Soviet Union, Communist Albania, China, and North Korea. The persecution of Christians has continued to occur during the 21st century. Christianity is the largest world religion and its adherents live across the globe. Approximately 10% of the world's Christians are members of minority groups which live in non-Christian-majority states. The contemporary persecution of Christians includes the genocide of Christians by the Islamic State and persecution by other terrorist groups, with official state persecution mostly occurring in countries which are located in Africa and Asia because they have state religions or because their governments and societies practice religious favoritism. Such favoritism is frequently accompanied by religious discrimination and religious persecution. According to the United States Commission on International Religious Freedom's 2020 report, Christians in Burma, China, Eritrea, India, Iran, Nigeria, North Korea, Pakistan, Russia, Saudi Arabia, Syria, and Vietnam are persecuted; these countries are labelled "countries of particular concern" by the United States Department