Mirwell is the westernmost of the Provinces, dominated by vast plains. South and east lie Wayman and L'Petrie Provinces, respectively, and Adolind to the north. The ruling Mirwells make their home in their stony keep in Mirwellton.

Most of the Mirwell line are militaristic in nature, and maintain a vast provincial army. Tomas Mirwell assisted in Amilton and Shawdell's attempt to assassinate Zachary to put Amilton on the throne. For his part, he was publicly executed by Zachary. His son, short and childish Timas, with Barret as his Steward, became the lord of Mirwell in his place. Because he was weak, in HKT, he was intimidated by Second Empire, notably Colonel Birch, who supplanted Beryl's place as counselor, to provide the Second Empire refugees for a place to stay, in the Teligmar Hills.

The warded prison-tomb of Mornhavon's ancient general Mirdhwell was located somewhere on the Mirwell plains. Mirwell's clan color is scarlet, and the title of each lord is "Warhammer."