In 1789, Alexander Mackenzie became the first European to travel the river that now bears his name. After his reports of rich fur resources reached the outside, the North West Company established fur-trading posts along the river. The Dene, who were originally nomadic, settled at the trading posts, forming small communities that still exist today.
The only road into the region begins at Fort Simpson [1] and extends north to Wrigley [2].
Links:
[1] http://www.moon.com/destinations/western-canada/northwest-territories/nahanni-country-and-the-mackenzie-valley/fort-simpson
[2] http://www.moon.com/destinations/western-canada/northwest-territories/nahanni-country-and-the-mackenzie-valley/towns-along-the-macken/wrigley