This kind of flute is present for many centuries, they say native Americans used them for ritual purposes, that's why sometimes it's called "love flute". 

Native American flute or pimak is a very simple flute to play, literally anyone without any knowledge about music instruments or wind instruments can produce beautiful music on these flutes after some practice, however native flutes are not so versatile as Irish whistles for example as you can't overblow it to another octave.