The Crystal Imperial Calendar and Very Brief History · 8:58pm Feb 9th, 2014
Years are counted from the semi-mythical founding of the Crystal City (which was at first called Lake Hill, and was then on the great lake which once occupied the majority of central northern North Amareica). This happened 447 years after the Cataclysm. The founders, who as the descendants of a university faculty knew about the computational problems of starting with a year 1, declared their first year to be "zero," facilitating conversions, so year 447 ATC is year 0 AUC (Anno Urbis Conditae). The year starts on the first day after the spring equinox, March 22nd (in our monthly terms).
The volkerwanderung of the Three Tribes that created Equestria (and which the Crystal City itself fended off with some difficulty) took place in the 7th century AUC. It was this crisis which helped topple the Republic and institute the Early Empire. The Early Empire expanded to rule the whole Northlands (including the original homelands of the Three Tribes). The coming of Discord in 991 AUC led to the contraction of the empire as Discord played with various provinces; the Age of Discord is also known as the Middle Empire. The defeat of Discord in 1991 AUC (after precisely a millennium of his dominance) led to an attempt at re-expansion which ran up against the greater strength of the Far Northern barbarians and the blocking of Southern routes of expansion by the Equestrian realms. This period is termed the Late Empire, and it is one of decadence, decline and despair.
The fifth foal of Carnelian and Citrine Quartz, Pentos, who would become Crimson Quartz and later known by a more famous regnal name, was born in 2430 AUC (439 Year Of Harmony in Equestria). The story Corruption at Nightfall begins in 2434 AUC (443 YOH), when he is three years old. The first chapter takes him to age 7, in 2438 AUC (447 YOH).
The Crystal City vanishes in 2480 AUC and reappears in 3485 AUC. To avoid major confusion, the Crystal Imperials simply advanced their calendar and accepted that they spent 1005 years in timeless stasis.
