Though no written records exist of the Kingdom of Sabrio, it is thought that it originated much the same way as early Cirsovan culture. The Kingdom of Sabrio originally consisted of communities along the Sabrio River valley which were at some point unified under a single king. Despite the dense rainforest growing around much of the valley, the communities were well connected by the river. Large swathes of forest were clear-cut along the banks, and in those clearings the cities of the old kingdom flourished. Indeed, by the time of the Second War of Unification, very little of the original forests remained, so many had been cleared away. Not content to remain a solely riparian power, the Kingdom of Sabrio pushed outward from the valley, displacing less settled peoples and encroaching on the territories of more civilized inhabitants.
During the war that destroyed the Kingdom of Sabrio, Orwen Akana saw to it that every city was thoroughly eradicated. The Imperial Legion moved up the river valley, from its mouth at the Dawnsea to its distant headwaters south of Brebea, a great cleansing fire through the land. The people of the Sabrio valley were, by the written accounts of the legion, wholly committed to evil, vice, debauchery and human sacrifice. The Empire today benefits greatly from their extermination.
Parts of the modern province of Karkuras, as well as large portions of Paelnor, were parts of the Sabrio Kingdom prior to the treaties of annexation which created those provinces.