The Sherpa were nomadic people who first settled in the Solukhumbu District (Khumbu), Nepal. According to Sherpa oral history, four groups migrated from Kham in Tibet to Solukhumbu at different times, giving rise to the four fundamental Sherpa clans: Minyagpa, Thimmi, Sertawa and Chawa. These four groups gradually split into the more than 20 different clans that exist today. Mahayana Buddhism religious conflict may have contributed to the migration out of Tibet in the 13th and 14th centuries and arrived in Khumbu regions of Nepal. Sherpa migrants travelled through Ü and Tsang, before crossing the Himalaya.