I find the term useful for Simpson hair, as super, 2-band, and Manchurian are all very distinct from one another. Rudy describes it well above.from Simpsons website :
"... using our own unique sourced rare High Mountain White Chinese Manchurian Badger. Two Band appearance, stiff shafts, uber-soft tips and the ultimate flow through qualities mean this hair is something truly unique in the industry."
+2! There is no established grading system for badger hair. This is cleaver marketing!Manchurian really does not say anything...its a pretty large area in the north east of China where a lot of badger hair comes from. I believe Simpson was the first company that named a certain grade of their badger hairs "Manchurian". Compared to their older two-band Super, this Manchurian hair is a thicker stemmed hair and a bit stiffer.
Now other companies jump on the name as well as it is just a good selling attribute. As Owen said, it is mainly used for a two-band hair, but I guess a three band coming from the area could be also called a Manchurian Three band...