Thyatis

The Empire of Thyatis is a powerful state in the Mystara campaign setting for the Dungeons and Dragons fantasy role-playing game. Thyatis was first mentioned in Module X1, Isle of Dread, which describes it briefly. Along with the Alphatian Empire, Thyatis was more fully detailed in the Dawn of the Emperors boxed set. Along with Alphatia, Thyatis is one of the "great powers" of Mystara.

Thyatis (the city) is the capital of the Empire and the largest city on Mystara. It is on the southeastern coast of the continent of Brun, situated between the trade lanes of the Sea of Dread to the south and the Sea of Dawn to the east, alongside a canal ("Vanya's Girdle").

Conceptually, Thyatis is a mixture of different parts of the various historical Roman empires. It is governed by an Emperor and an Imperial Senate as per the classical Roman Empire, but enfranchises a feudal noble class similar to that of the Holy Roman Empire. The Emperor himself is akin to that of the Byzantines (as is the capital city's placement on a major strait). The Imperial Bureaucracy as described in Dawn of the Emperors is clearly inspired by that of the British Empire, as is, at least in name, one branch of the Thyatian Armed Forces, the "Retebius Air Corps" (RAF), which consists of cavalry on flying mounts (Pegasi, Hippogriffs, Griffons, Sphinxs, Rocs, and Dragons).

Karameikos is ruled by a Thyatian nobility, but the Empire's territories consist of the western half of the Isle of Dawn, the island realms of Ochalea and the Pearl Islands, and the Thyatian Hinterlands on the southern continent of Davania, in addition to its mainland territories on Brun, which are the smallest of the Empire's territories by geographic size, but the most heavily populated and developed of them. The total land area of the Empire is approximately 800,000 square miles (2,100,000 km²). Because of its political geography, Thyatis can best be described as a thalassocracy.

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