First contact with European fur traders expanding into the region occurred in the 18th century, and was increased with Alexander Mackenzie's exploration of the Mackenzie River (Deh Cho), and building of trading posts at Fort Simpson and Fort Liard. At both of these John McLeod, a Scottish explorer of the area, was to serve as manager. During the 19th century, most Dene families left their nomadic lifestyles and settled into more permanent communities, often close to the trading posts. Permanent settlements were established at locations such as Nahanni Butte, Fort Liard and Fort Simpson.