Can anybody give me an "In-depth" history lesson on Yi Quan?

I never really thought about it until recently, and many of it's concepts and ideas are so intruging, logical, and out of the box! It's something unique, yet it isn't really known outside of the Gong Fu world... The idea that it doesn't use qi, yet it is considered an internal martial art is odd. Could it originate from the Muslim side of Gong Fu? Thanks!