The 13~month, 28 day alternative has been in use on this planet for more than 6000 years. In prehistoric Indi and China, and throughout South America it was the standard time~keeping system. The Essenes, Egyptian, Polynesian, Maya, Inca, Lakota, and Cherokee used a 13~month, 28 day calendar. the Celtic knowledge of the Druids is based on the tree Calendar, also a 13~month, 28 day calendar. Today many cultures are still using their traditional 13~month calendar system.