One of the larger duchies in south-central Dragaera. The duchy was named by the Lyorn Lord Corpet, who financed the expedition that finally settled the region. It was named for the leader of the settlement expedition, a Dzurlord named Arylle, and is located to the north of the Duchy of Luatha, and directly to the east of the Collier Hills, alongside the Yendi River. Founded as a county, the area was raised to a duchy during the ninth Vallista reign, as a favor to Corpet's daughter, who aided the Emperor in a conflict with certain rebellious factions within the Empire.