Throughout its history, between 3,200 and 6,000 students died while attending the Canadian Indian residential school system. The exact number remains unknown due to incomplete records. Comparatively few cemeteries associated with residential schools are explicitly referenced in surviving documents, however the age and duration of the schools suggests that most had a cemetery associated with them. Most cemeteries were unregistered, and as such the locations of many burial sites of residential school children have been lost. The Truth and Reconciliation Commission of Canada has called for "the ongoing identification, documentation, maintenance, commemoration, and protection of residential school cemeteries or other sites at which residential school children were buried."