Duchy granted Cas bel-Taren as his reward and dowry upon his wedding to Sia bel-Aruthien. The Cassian March stretches from the Greatwood in the east to the sea in the west, from Kravak-Barr in the north to the mountain Tolwyn's Throne in the south.
The Duchy is populated by a very mixed population of races; everything from Men Elves to Flen and Ansvar. The City of Tir Castellan has sections populated solely by members of the major races, with other zones hosting multi- racial groups or rare beings, including resident Sea Witches, Dryads, and some friendly Dragons.
External threats to the Duchy are numerous. To the west are the scattered remnants of the Jarls, who live like nomads along the coast. To the south, Jotunn and other small tribes roam the countryside between Tir Castellan and Aligindel. To the east is the dense thicket of the Greatwood, north of that the Shardstone Plain and it's hostile Centaurs, and north of that, the Jotunn stronghold of the Vigabrock. Directly north of Tir Castellan is Kravak-Barr, the lost Dwarven hold, which is brimming with hostile races and ancient magics. Beyond Kravak-Barr lies Olangsapp, stronghold of the Owl Jotunn, which bars the way to the Cameran Highlands. North of Olangsapp lies the desolate Redstone Spur, home to a pair of ancient hostile Dragons. Only stout walls and constant patrols by the Duchy's soldiers keep the hardy frontier folk safe.