guzheng only grew in the far south. It would be redesigned later to imitate and use curved boards like the Se to replace the curved half-tube of bamboo. It was also said to have evolved from the Se. In their current form, both instruments are what are described to be board zithers rather than half-tube zithers. The Japanese Koto is also a half-tube zither. The ancestor of the koto was the Chinese guzheng. It was first introduced to Japan from China in the 7th and 8th century. The first known version had five strings, which eventually increased to seven strings. (It had twelve strings when it was introduced to Japan in the early Nara Period (710–784) and increased to thirteen strings). The Japanese koto belongs to the Asian zither family that also comprises the Chinese (ancestral to the other zithers in the family), the Kazakh , the Korean , and , the Mongolian , the Sundanese and the Vietnamese . Parallel-Stringed Half-Tube Zither The bamboo half-tube zither found in the Philippines among the Ifugao is called , , , or . It has two to four strings which, depending on the style of playing, are plucked with the fingers or struck with small bamboo sticks. Boys and men play the tadcheng for entertainment, often tapping rhythms patterned after those played on the gongs. The Ibaloi of North Luzon also have a half-tube polychord tube zither which they call the kaltsang . Bowed tube-zithers Mergui Archipelago, Burma and Thailand The Moken people, who live in the Mergui Archipelago in the southern end of Burma, have a two-string bamboo-tube zither, the which they pluck and bow. The instrument, made from a tube of bamboo about 622 millimeters (24.48 inches) long and 48–52 mm (1.8 — 2 inches) across, was originally strung with plant fibers or gut from sharks or dogs. The Moken have modernized their instrument, using nylon fishing line in place of the plant or gut strings. One long string is folded in half and the folded bight is hooked onto the lower end of the instrument. The two string-ends are each tightened and tied at the top of the instrument. The strings are held off the bottom of the instrument with a bridge. The bow is made of bamboo, with a strip of rattan for a bowstring and bee's wax for rosin. The bamboo tube is closed at the bottom