The Slaves of House Hezzrat
The Athasian Calendar Every city state has its own calendar, but that most commonly used and considered the Calendar of Tyr. In the calendar of Tyr, years are counted off using a pair of concurrently running cycles; one of eleven parts, the other of seven. The eleven-part, or endlean cycle, is counted and spoken first, in the order presented below. The seven-part, or seofean cycle, is counted and spoken second. The endlean cycle is complete when Athas two moons, Ral and Guthay, meet in the heavensa major eclipse that occurs once every 11 years. The seofean cycle is more abstract, meeting when agitation in the cosmos leads to fury.
Every 77 years the cycle repeats itself, ending with a year of Guthays Agitation and starting again with a new year of Rals Fury. Each 77-year cycle is called a kings age; there have been 183 complete kings ages since Tyr adopted this calendar (more than 14,500 years).So, the first year of each kings age is a year of Rals Fury. The next year is a year of Friends Contemplation, followed by a year of Deserts Vengeance, etc. The 76th year of each kings age is a year of Enemys Reverence, followed by the 77th year, a year of Guthays Agitation.
Superstition and folklore surrounds each of the years of the kings age. Storms during a year of Winds Vengeance are believed to be more powerful and dangerous, so many overland trips are avoided. Sacrifices and prayers are called for to ward off the great beast during years of Dragons Agitation. Years of Enemys Contemplation are supposed to enliven treaties and alliances-the list goes on.
Each year is made up of exactly 375 days: the exact time between highest suns. Athasians have no seasons that govern their thinking of time-there is no marked difference in temperature or weather patterns. However, the year is divided into three equal phases: high sun, sun descending, and sun ascending. Highest sun is the first day of the year in the calendar of Tyr and lowest sun indicates the midpoint of the year (which, incidentally, occurs at midnight, and is generally observed in nighttime ceremonies).
Days are kept track of in a variety of ways. Merchants tend to identify days with phrases such as thirty five days past the high sun. Other schemes divide the year into 25 weeks of 15 days each, the names of those days associated with important personages of a particular royal house. In DARK SUN campaigns, DMs may stick to seven day weeks with the standard Gregorian calendar names for simplicity.
Every 45 years, a brilliant comet visits Athas. By night one can read by the messengers light, and it can be seen clearly in the full light of day. Folklore holds that the messenger visits the dragon every 45 years to deliver to him important information reconnaissance that the stars have observed since its last visit.
From: Dark Sun Rules book. pg. 85© 1991 TSR, Wizards of the Coast, Hasbro… or whoever owns it. this is not my information, but from their books.