The Dayak or Dyak are a people indigenous to the island of Borneo. It is a loose term for over 200 riverine and hill-dwelling peoples, each with their own dialect, customs, laws, territory and culture.
Some of the more well-known Dayak Peoples include the Kayan and Kenyah, the Ibans, the Penan, the Ngajus and Baritos.
Adapted from Wikipedia article on the Dayak People.