This was the center of the Jesuit missions and settlements in this part of South America in the eighteenth century, which included portions of Uruguay, Argentina, and Brazil. They developed Jesuit Reductions to bring Indian populations together at Spanish missions and protect them from virtual slavery by Spanish settlers, in addition to seeking their conversion to Christianity. Catholicism in Paraguay was influenced by the indigenous peoples; the syncretic religion has absorbed native elements. The reducciones flourished in Eastern Paraguay for about 150 years, until the expulsion of the Jesuits by the Spanish Crown in 1767. The ruins of two 18th-century missions have been designated as World Heritage Sites by UNESCO.