An attempt to create an autonomous Christian Indian nation was undertaken by Jesuit missions and settlements in this part of South America in the eighteenth century. They developed Jesuit reductions to bring Guarani populations together at Spanish missions and protect them from virtual slavery by Spanish settlers and Portuguese slave raiders, the Bandeirantes, 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 Jesuit Missions of La Santísima Trinidad de Paraná and Jesús de Tavarangue have been designated as World Heritage Sites by UNESCO.