It supposedly comes from originaly counting in base 20 ( a.k.a : vigesimal system) in some proto-european language. There are traces of it in breton, albanese, basque and danish for example. Even in english, there is a reminiscence of vigesimal, in the “score”, see for example Lincoln’s Gettysburg Address which famously starts with : “Fourscore and seven years ago…”, meaning 87 years ago.