Metlakatla Pass, or Venn Passage, is located 4 km west of Prince Rupert on the northern BC coast. It is a narrow, protected channel that extends over 5 km, and separates Digby Island from Tsimpsean Peninsula. The area is noted for its density of archaeological sites: archaeologists have discovered 40 sites along its shores. These sites include 27 shell middens that indicate the presence of ancient Indian villages. The remaining 13 sites are petroglyph or rock art sites, which consist of low-relief carvings on boulders or rock outcrops (see pictographs and petroglyphs). The people who occupied the area at the time of European contact were the Coast Tsimshian. Traditionally, all 9 tribes of Coast Tsimshian had permanent winter villages in the Metlakatla Pass area. Excavations conducted at several of these village sites from 1966 to the 1970s suggest that Metlakatla Pass has been occupied for approximately 5000 years. The Metlakatla Pass area was made a National Historic Site in 1972 because of its importance in Canadian history.