The Psaltery is a revived instrument that died out in the middle ages along with it's playing tradition which is lost to us (the Bowed Psaltery is a modern invention for Folkies, essentially a simplified Ukelin, invented by Marx in the 1920s). We hear how the crusaders brought back various instruments from the Holy Land that formed the basis of many medieval instruments and that the Psaltery was derived from the Qanun which thrives in Arabic classical & popular music to this day. Lots of excellent examples on YouTube as you'd expect, including this choice cover version:

Metallica Nothing Else Matters played with Qanun