Is the santoor related to the yangqin and the cimbalom?

Yes, the santoor belongs to the family of hammered dulcimers: box zithers whose strings are struck with a pair of light mallets. Its relatives include the Persian and Iraqi santur, the Chinese yangqin, the Hungarian cimbalom and the German Hackbrett. In Kashmir the santoor was used for centuries mainly to accompany singers of Sufiana Mausiqi, the Sufi-related classical music of the region.