Religious missions have been divided into 'foreign' and 'home' categories. 'Home' category missionaries deal in particular with the poverty stricken, the homeless, and the social outcasts or misfits.
Those in 'foreign' categories mainly deal with indigenous peoples on whom they may impose a totally new moral code to which tribespeople find it very difficult to adapt. Often missionaries tell the people that their customs are primitive and barbaric, and use education and comparison with western ways to embarrass the young people into disowning their cultural values and practices. But having done so, native peoples may find themselves dependent on 'Western' economic and social structures. Because they are inadequately educated and discriminated against on an ethnic basis; and because they have little experience in market economic structures, this dependence renders them easy prey to exploitation, poverty, disease, malnutrition and death.
Buddhism, Zoroastrianism and Judaism were once missionary religions. Christian missionary activity began in the early years after the death of Christ. It spread to all parts of the Roman Empire. Christian missionaries pressed eastwards into Russia and Asia as far as China. From the 15th to the 18th century Roman Catholicism became a world religion with the thrust of Spanish and Portuguese colonialism. From 1750 to 1815 the Catholic missions were in decline. Protestantism was slow to undertake missions but this changed with British imperialism and continued to expand during the 19th and 20th centuries. Islam spread from Southeast Asia to the Atlantic coast of Europe and from central Europe to both coasts of central Africa by the middle ages. It currently has missionaries in Europe, the Americas and Africa.
In 1994 China banned proselytizing by foreign missionaries because of their tendency to engage in destructive, independent and unauthorized activities inspired by culturally insensitive values. Activities by Christian missionaries have provoked riots by China's Muslim minority. Churches there have been accused of harbouring political dissidents.