Bansuri is a flute of  India  made from a single hollow shaft of bamboo with six or seven finger holes. An ancient musical instrument associated with cowherds and the pastoral tradition, it is intimately linked to the love story of  Krishna  and  Radha. There are two varieties of bansuri: transverse, and  fipple. The  fipple  flute is usually played in folk music and is held at the lips like a  whistle. Because it enables superior control, variations and embellishments, the transverse variety is preferred in Indian classical music. The index, middle, and ring fingers of both hands are usually used to finger the six-hole bansuri.  As with other air-reed  wind instruments, the sound of a bansuri is generated from  resonance  of the air column inside it. Bansuri construction is a complex art. The bamboo suitable for making a bansuri needs to possess several qualities. It must be thin walled and straight with a uniform circular cross section and long internodes. Being a natural material, it is difficult to find bamboo shafts with all these characteristics, which in turn makes good bansuris rare and expensive. Suitable species of bamboo (such as  Pseudostachyum) with these traits are endemic to the forests of  Assam  and  Kerala.