The Modern Era is the third eon of Alarian history, and the one the living world still stands inside. It opens at the close of Hykravones the Shattering — roughly 13,500 years ago, 10,209 BSD — when the Gray Prince stopped breaking the world and went to ground. What he left was a near-empty stage: most daemons dead with their worshippers, civilization thrown thousands of years backward, the survivors scattered. Everything since has been built up from that.
The eon carries the seam that defines all civil dating. Its long first age is reckoned in BSD; its current age in SD; and the two meet at calendar zero, the boundary the surviving calendars fixed just after the World Fire. By the older pattern, the eon is young and unfinished. The first two eons each ended in a single reality-warping catastrophe, and the more careful record-keepers do not assume the third will be spared one.
The Great Expansion: 9,950–0 BSD
The first age was the long rebuilding. Survivors spread back across a ruined world, weathered the Frost Fall when the water plane pressed close and the south went cold for a century and a half, and learned to live with dragons creeping back into prominence. It closed at calendar zero, the decade after the World Fire (~10 BSD), when a lone fire-paragon over-channeled the Yolus seam until it ruptured and fire poured loose across the world. The surviving calendars set their zero in the burning's aftermath, the boundary between the BSD reckoning and the SD age. Both the recovery and the fire carry their own entries: era-great-expansion and era-world-fire.
The Seventh Dawn: 0 SD–present
The current age counts forward from the World Fire. Its opening centuries were the Dark Ages, when the Titansworn — a cult that mistook the burning for titan-wrath and labored to wake Hykravones against a recurrence that was never coming — had to be put down by war before anything stable could grow. Out of that came the political world of the present: the prayer-coalitions and the Solar Accord they signed to stop killing one another over the harvest, the empires built on straits and sacred fire, the standing disputes a traveler walks into today. The age runs to 3376 SD and its catastrophe has not arrived. The full account is in era-seventh-dawn.