The Chumash tribe (not the principles) were played by the Manchester and Kashia tribes of the Pomo nation.
This movie is based on the Newbery Award-winning book "Island of the Blue Dolphins" by Scott O'Dell. The book is based on the true story of a woman left behind on the Channel Islands by missionaries in the early 1800s. She lived alone on the one of the islands for 18 years and died of dysentery seven weeks after she was "rescued" and brought to the mainland. She is buried in the graveyard of the Santa Barbara Mission in California.