The Persian santoor is a three-octave wooden-hammered dulcimer with seventy-two strings, which are arranged on adjustable tuning pegs in eighteen quadruple sets, nine (bronze) in the low register, and nine (steel) in the middle register. The santoor can be made from various kinds of wood (walnut, rosewood, betel palm, etc.) depending on the desired sound quality. The front and the back of the instrument are connected by sound posts whose positions play an important role in the sound quality of the instrument. Although the santoor is very old, it was neither depicted in miniatures, nor presented in any other medium until the nineteenth century. The secret of making the trapezoid-shape sound box lies in the quality and age of the wood, as well as in the arrangement of the sound posts which connect the table of the instrument to its back. Santoor is played in India, Iraq, Egypt and some other countries. In some references santoor is spelled as santur or santour.