As the name implies, the "Known World" covers the most notable nations of Mystara, the ones most commonly used in Mystara-based campaigns and featured in fiction. It includes the Thyatian Empire, which could be compared to Byzantine Empire; the Grand Duchy of Karameikos (which includes the town of Threshold, the default setting of many classic D&D adventures), comparable to medieval southeastern Europe; the Principalities of Glantri, which is similar to medieval western Europe, ruled by wizard-princes; the Ethengar Khanate, a Mongol-like society; the merchant-run Republic of Darokin, which is based somewhat loosely on the mercantile states of Medieval Italy; the Emirates of Ylaruam which have an Arabic flavor; the Heldannic Territories, ruled by an order of religious Knights devoted to the Immortal Vanya, similar to the Teutonic Knights; the Atruaghin Clans, which have an Amerindian feel; the nation of Sind, based on India during the rule of the Mughals; the Northern Reaches Kingdoms of Ostland, Vestland, the Soderfjord Jarldoms, based on Scandinavian kingdoms at various periods of history; the Dwarven nation of Rockhome; the elven Kingdom of Alfheim; the Halfling lands of the Five Shires; and the Alphatian Empire, ruled by wizards and other spellcasters.