Huqin 胡琴 is a family of bowed-string instruments found in China that is descended from Xiqin 奚琴. It
differs from violins and other bowed-string instruments that horse hairs of the bow are kept between two strings (or sometimes even three or four strings). 

Xiqin, the ancestor of Huqin family, got its name from the tribe of Xi, also known as Kumo Xi 庫莫奚, a nomadic tribe that lived somewhere between the Mongolian steppes and Manchuria from the 3rd to the 10th century. It is closely related to another nomadic tribe Khitan 契丹 (Cathay).

It is not easy to get any clues from the name Xiqin, which is a transliteration of Mandarin. However, in Cantonese, a language that bears more resemblance of medieval Chinese of Song dynasty, Xiqin is pronounced as Haikam. And now you may see that this word sounds very similar to a Korean instrument haegeum 해금, which shows that they are originated from the same root.  

Now let's talk about the name of this family of bowed-string instruments, huqin 胡琴. The name Hu 胡 is usually a term that Chinese used to signify anything that comes from the nomadic tribes in the north. Some theories said that it is a transliteration of khuur, as related instrument such as Morin khuur (морин хуур / 馬頭琴) existed in Mongolia. 

As time progressed, this family of instruments is adopted by Han Chinese, with its various forms taking leading role in operatic music. Erhu 二胡 is a modern form that is popular as a solo and ensemble instrument, developed in the Ming and Qing dynasty and standardised in the 20th century. 

(More about the instrument will be discussed soon.)