It's difficult for many to comprehend today, but there was a time when Kirkwall was believed to be the very edge of the world.
It was Emerius then, named after its founder Magister Emerius Krayvan, and it was but one outpost on the very fringe of the Tevinter Imperium. There the magister's serfs worked at the quarries for the jet stone needed for the mighty temples of Minrathous. After a slave rebellion nearly burned the temple to the ground in the great city, it was determined that a center for slave trade would need to be established well away from the more civilized parts of the Imperium. (Though account may be exaggerated, since the notorious Archon Vanarius Issar narrowly escaped assassination at the hands of an elven slave at the time.)
Because the new slave outpost would become wealthy beyond imagining, competition among prospects reportedly took over twenty years to resolve, resulting in great bloodshed in the frontier, well away from the archon's eyes. Magister took arms against magister, mostly in the form of small armies of serfs and mercenaries. Over half the slaves in existence allegedly died in these battles before Emerius was finally chosen, thanks to the marriage of Krayvan's son to the archon's daughter.
Within a mere decade, the mighty fortress was erected on the cliff where Kirkwall now stands. Over one million slaves passed through its gates before the Imperium eventually fell, an unimaginable number by today's standards. The Krayvan family itself became patrons of the next three archons and was one of the driving forces behind the extension of the Imperial Highway into the Ferelden Valley, a move that would cost them considerable political influence after the resistance of the Alamarri tribes. During its height, Emerius was a jewel to rival the mightiest of the Imperial cities and the greatest center of civilization outside Tevinter.