The Karmapas are a lineage of tulkus, or reincarnated lamas, and heads of the Karma Kagyu tradition of Tibetan Buddhism, recognizable by their distinctive black hats. They began tracing their reincarnations starting in the thirteenth century when Rangjung Dorje (1284–1339) recognized himself the reincarnation of two predecessors, to whom he gave the titles Second and First Karmapas. The Karmapas are thus the historically oldest tulku lineage in Tibetan Buddhism. The Karmapas were a major force in medieval Tibet, but their economic and political power was broken in the mid-seventeenth century when the Geluk-tradition Dalai Lamas and their Mongol allies defeated the king of Tsang and drove many Karma Kagyupas into exile. Nevertheless, the Karmapa lineage survived, and remains influential today. The Karmapas are believed to be emanations of the bodhisattva Avalokiteshvara.