Although the crown recognized the political structures and the ruling elites in the civil sphere, in the religious sphere indigenous men were banned from the Christian priesthood, following an early Franciscan experiment that included fray Bernardino de Sahagún at the Colegio de Santa Cruz Tlatelolco to train such a group. Mendicants of the Franciscan, Dominican, and Augustinian orders initially evangelized indigenous in their own communities in what is often called the "spiritual conquest". Later on the northern frontiers where nomadic indigenous groups had no fixed settlements, the Spanish created missions and settled indigenous populations in these complexes. The Jesuits were prominent in this enterprise until their expulsion from Spanish America in 1767. Catholicism with particular local aspects was the only permissible religion in the colonial era.