This is a bow made to resemble a manchu bow of the late 18th century, but it is shorter featuring wide limbs.
 
The short length makes it ideal for people with shorter draw length，ideally 30" to 32",  so that they can gain more arrow speed than shooting the full size manchu bows. The wide limbs make it more resistant to twist as well as shoots more accurately.
 
The name of the bow is dreived from the First Jinchuan Campaign (1747-1749). In the campaign, the Qing imperial army overcame great logistic difficulties to fight the hardened rebel forces of two Gyalrong chieftains ("Tusi") from the Jinchuan region---modern day western sichuan province, a mountainous region leading up to the tibetan plateau. The name "Jinchuan" means “goldern river” in chinese and is derived from the tibetan pronouncication of "big river". 
 
The Jinchuan region is rich of rivers, valleys, forests, and constant rains,making the climate cery challenging to the horn-sinew composite manchu bows the Qing army had at that time. For this reason the Emperor orderd some short siyah, wide limb bows be made his soldiers.
 
For more information of the historical event please check out this page:
https://www.mandarinmansion.com/article/jianruiying-introduction
 
Brace Height: 17-19cm
Minimum Arrow Weight: 10 gpp if draw less than 31", 12 gpp if draw more than 31".
String Length: 139cm
Draw Weight: 20lbs to 50lbs @ 28''
Maximum Safe Draw Length: max 33'' up to 40lbs draw weight; max 32" over 40lbs draw weight