Khanjani is a percussion musical percussion instrument, a variety of Daf, found in West Bengal & Odisha. After the hard work in the field all farmers and villagers gather in a small club (which is called "tungi" ) at evening and sing songs and use this musical instrument which is call Khanjani. This is usually created from the sell of the Snake, Cow and Crocodiles.
References
Khanjani Wikipedia(Text) CC BY-SA