The zodiac was originally on the ceiling of the Hathor temple in the city of Dendera in Egypt, where the mysteries of the resurrection of the god Osiris were celebrated.
With the permission of Egyptian ruler Mohamed Ali Pasha, the zodiac was cut down and taken by Napoleon to France in the 19th century.
On the inside wheel are the twelve signs of the zodiac, and then in the middle wheel are the 36 decans. A full description of the original Zodiac of Dendera can be read on http://www.louvre.fr/en/oeuvre-notices/zodiac-dendera
In this video author Stephen Mehler suggests that this system was invented after a great cataclysm wreaked havoc on our planet some 11,500 years ago.
A video of the original Zodiac of Dendera from the Louvre in Paris, taken on May 19, 2007.