Depictions of the pear-shaped pipas appeared in abundance from the Southern and Northern Dynasties (420 to 589) onwards, and pipas from this time to the Tang Dynasty were given various names, such as Hu pipa (胡琵琶), bent-neck pipa (曲項琵琶, quxiang pipa), some of these terms, however, may refer to the same pipa. Apart from the four-stringed pipa, other pear-shaped instruments introduced include the five-stringed, straight-necked, wuxian pipa (五弦琵琶, also known as Kuchean pipa (龜茲琵琶)), a six-stringed version, as well as the two-stringed hulei (忽雷). From the 3rd century onwards, through the Sui and Tang Dynasty, the pear-shaped pipas became increasingly popular in China. By the Song Dynasty the word pipa was used to refer exclusively to the four-stringed pear-shaped instrument.
