In 1967, Canada became 100 years old, an event which was widely observed and celebrated. Many municipalities sponsored tokens and medallions to mark the Centennial.
As for Yellowknife (capital of the Northwest Territories), I have a special collection of stuff from the Territories. Tokens, medallions, lapel pins, buttons... if it's cheap and it's from Canada's far North, I'll usually buy it.
So I was pretty happy to find a Centennial medallion from Yellowknife at the Edmonton Coin Show today:

The antiqued design is really sharp - I would say this is one of the nicest-looking medallions I own.