The music that I picked is called 高山流水 "Mountain High, River Swift" (also translated in different ways as "High Mountain Flowing Water" and variations thereof). It is one of the pieces recorded in the oldest book of written music recovered, dating back to the 1400s. The version we have now has been updated since then, but it still follows the original form quite closely. It also has multiple parts/movements, but most modern rendition of this is limited to the shorter version in this video. For those into music, the main body of the wiki entry talked about the characteristics of the instrument and the differences between the instrument used for tradition versus modern compositions.
Oh, yes, it's a calming, peaceful sort of instrumental. It is supposed to evoke the images of a high, forested mountain, and a swift running stream. Enjoy.