This bow is a speculation of one of the bows used in the Yuan dynasty, the mongol dynasty that ruled China from 1279-1368. 
 
It is of the classical long siyah short limb design, but the siyah is becoming more reflexed---a feature found on bows that come later. 
 
String length: 126cm
Max Draw length: 31''
Draw weight: 20 to 50lbs @ 28''