AFAIK the system goes back to the old Babylonians who had a base-60 system subdivided into 5 times 12. 5 times 12 could easily be counted using your thumb to count the 12 knuckles on the other fingers and the 5 fingers of the other hand.

I mean, how amazing is counting like that! I only learned to count to 10 with my fingers. I love the base-10 for its simplicity but base-60, subbase-12 is the shit :D