The purpose of the mission settlement was threefold: to convert Indians to Christianity; to teach them the ways of Spanish civilization; and to hold the land for Spain. The friars taught the Indians their religion, language, customs, how to plant and harvest crops, and a variety of skills and crafts. Since the missions were agencies of the state as well as of the church, Spanish law was carried to the frontier and became a permanent part of subsequent civil law in both Mexico and the Southwestern part of the United States. Toward the end of the 18th Century, Spain pulled its line of settlements south toward Mexico, and she fortified only the mission settlements in San Antonio, El Paso, and Goliad as frontier outposts of Spanish authority. The stamp of Spanish culture was so strong, however, that it remains to this day in Texas and the Southwest.