A Christian mission is an organized effort for the propagation of the Christian faith. Missions involve sending individuals and groups across boundaries, most commonly geographical boundaries, to carry on evangelism or other activities, such as educational or hospital work. Sometimes individuals are sent and are called missionaries, and historically may have been based in mission stations. When groups are sent, they are often called mission teams and they do mission trips. There are a few different kinds of mission trips: short-term, long-term, relational and those that simply help people in need. Some people choose to dedicate their whole lives to mission. Missionaries preach the Christian faith (and sometimes to administer sacraments), and provide humanitarian aid. Christian doctrines (such as the "Doctrine of Love" professed by many missions) permit the provision of aid without requiring religious conversion. However, Christian missionaries are implicated in the genocide of indigenous peoples. Around 100,000 native people in California, U.S., or 1/3 of the native population, are said to have died due to missions.