These mittens have long, wide cuffs to help stop the wind from finding its way up your sleeves, and a narrow ribbed wrist to hold them in place. This shape was common on the Swedish island of Gotland.
The colourwork patterns are from the Turkish tradition, but combined in the Nordic way, with different patterns on the cuff, back, palm, gusset and thumb. The top of the mittens and the thumbs are worked in smaller patterns, much like the toe portion of the sole on Turkish socks.

The mittens are worked using a simplified version of the traditional Swedish technique tvåändsstickning (twined knitting). Twined knitting produces a firm fabric that’s warm and windproof.
Traditionally, the strands are always twisted in the same direction on the wrong side of the fabric, which makes it necessary to stop every so often to untangle the yarn. In this simplified version, the strands are twisted one way on one round, and the other on the next, making it easier to manage the yarn. This will give a herringbone effect on the inside of the mittens, much like the herringbone braid at the beginning of the cuff.
To make it easier to remember which way to twist, pick up the working yarn over the previous colour on even rounds, and under the previous colour on uneven rounds. Make sure to never work more than three stitches without twisting the yarn. For a good video tutorial on the twined knitting technique, take a look at http://bit.ly/twinedknit
If you prefer, you can work these mittens using the Fair Isle technique instead.