Although The Mix was published as part of the Thesis superfamily of fonts in 1994 when it was originally named Fontfont, its origins go back to when designer Lucas de Groot was working in Holland for the Dutch Government. The The Mix font began as an alphabet for the font logotypes in the logo for the Dutch Ministry of Transport, Public Works and Water Management. DeGroot designed them while he was employed by BRS Premsela Vonk in Amsterdam.

Later, when de Groot decided to explore a way to create a more harmonious and yet versatile set of fonts for use in corporate identity work, he began with TheMix as a starting point for what was to be his trio of fonts: The Sans, The Mix and The Serif that together would comprise the superfamily Thesis, This concept of creating a superfamily of fonts that would offer a set of compatible styles in a range of weights was soon to be seen as an important tool for typographers.

The concept for The Mix was to create a corporate identity font that would be young and fun. It had an unorthodox character to it that made it perfect for campaigns that focused on image or in advertising that had youthful audiences as its primary target.

References:
http://typedia.com/explore/typeface/thesans/
http://www.lucasfonts.com/fonts/themix/about/
http://www.identifont.com/show?1M
http://www.fonthaus.com/fonts/lucasfonts/Thesis-TheMix

The Mix has a habit of showing up in a wide variety of places. If you are arriving in Berlin’s Hauptbahnhof (Central Station) you will see that all of the signage is in TheMIx. In England, British Gas has TheMix as the font of its corporate logo as well as using it as its headline font throughout all of its publications. In Belgium you will see the font TheMix all around you as it is used by the Belgium Police for all of their public signs.