The first inhabitants of North America are generally hypothesized to have migrated from Siberia by way of the Bering land bridge and arrived at least 14,000 years ago. The Paleo-Indian archeological sites at Old Crow Flats and Bluefish Caves are two of the oldest sites of human habitation in Canada. The characteristics of Indigenous societies included permanent settlements, agriculture, complex societal hierarchies, and trading networks. Some of these cultures had collapsed by the time European explorers arrived in the late 15th and early 16th centuries and have only been discovered through archeological investigations.