The title Dalai Lama, from the Mongolian for Ocean, meaning teacher of vast wisdom, was first bestowed in 1578 by the Mongol ruler Altan Khan on Sonam Gyatso, the third head of the Gelug reincarnation lineage; two earlier teachers were recognized retroactively as the first and second Dalai Lamas, so continuity was asserted backward as well as forward. The office combined spiritual and, from the seventeenth century, political authority: the fifth Dalai Lama, Ngawang Lobsang Gyatso, unified much of Tibet under his rule in 1642 with Mongol military backing and founded the Ganden Phodrang government that administered Tibet, with interruptions, until the mid twentieth century.
Within the Gelug school, the largest of the four principal schools of Tibetan Buddhism, the Dalai Lama is regarded as an emanation of Avalokiteshvara, the bodhisattva of compassion, though the office's religious authority is distinct from, and traditionally subordinate on strictly doctrinal questions to, the Ganden Tripa, the Gelug school's elected head. Politically, Chinese forces took control of Tibet in 1950 and 1951, and the fourteenth Dalai Lama fled to India after a failed 1959 uprising, since which the office has functioned as a government in exile and a global religious and diplomatic presence rather than a ruling government inside Tibet.