Alphatia refers both to a continent and an Empire in TSR's fantasy game setting, Mystara. The Continent of Alphatia is nearly 2,000,000 square miles in area and has approximately 7,500,000 inhabitants. The continent of Alphatia is the center of the Alphatian Empire.
Unlike most humans on Mystara, Alphatians are an "alien" human race, having arrived from another plane after they destroyed their original Empire. The Alphatian people consist of two sub-races, the pale-skinned, dark-haired "pure" Alphatians and the more common copper-skinned "Cypri" Alphatians.
Alphatia is a large Empire within the Mystara campaign setting. It is located east of the continent of Brun and west of Skothar. It is a large Imperial Magocracy (ruled by spellcasters), consisting of numerous Kingdoms loosely united under the rule of an Emperess. In the module CM1, Test of the Warlords, three crones call Alphatia "Atlantis". This direct reference is not repeated again in canon, but Alphatia is partly inspired by Plato's description of Atlantis, and its ultimate fate draws upon the legend of Atlantis. However, the Dawn of the Emperors boxed set, which details both Alphatia and The Thyatian Empire, gives Alphatia a unique flavor.
The territories of Alphatia include the island-continent of Alphatia itself, the somewhat smaller island-continent of Bellisaria, the eastern half of the Isle of Dawn, the Alatian Isles south of the Isle of Dawn, Esterhold, a large peninsula of Skothar, and the disputed lands of The Kingdom of Norwold. Alphatia's capital is Sundsvall, the "City Built by Magic", a large city in south-central continental Alphatia. Sundsvall is also the capital of the Kingdom of Vertiloch, which is ruled directly by Alphatia's reigning Empress Eriadna. Other major cities include Aasla, in the Kingdom of Haven, and Draco in the Kingdom of Stonewall, both of which are port cities.
Alphatia's traditional rival is the Western Empire of Thyatis, which was ruled by Alphatia for two centuries (BC 192 - BC 2) until it successfully rebelled and carved its own Empire out of former Alphatian territories. In the AC 1000 timeline, the two powers are locked in a fantasy version of the Cold War.
Alphatia is ruled by an Emperor or Empress who is advised by a Council of Wizards. The power of the Empire is mitigated by the fact that Alphatia's fractious Kingdoms, with their own rulers, are only loosely controlled and normally very hard for the central government to coordinate. An exception to this came in the Wrath of the Immortals, where immortal interference caused the normally disunited and chaotic Alphatians to unite in the cause of destroying The Principalities of Glantri. At the end of this campaign, the continent of Alphatia was destroyed, though numerous Alphatian kingdoms on the imperial fringe remained active.
After the events of The Wrath of the Immortals, the main continent of Alpatia and its population were rebuilt by the Immortals as a floating continent in the Hollow World.