The Principality of Achaea or Principality of Morea was one of the vassal states of the Latin Empire, which replaced the Byzantine Empire after the capture of Constantinople during the Fourth Crusade. It became a vassal of the Kingdom of Thessalonica, along with the Duchy of Athens, until Thessalonica was captured by Theodore, the despot of Epirus, in 1224. After this, Achaea became for a while the dominant power in Greece.
Achaean tornese from Glarentza (Clarentia)
Ruins of the 13th-century St. Sophia church in Andravida
The Latin Empire, also referred to as the Latin Empire of Constantinople, was a feudal Crusader state founded by the leaders of the Fourth Crusade on lands captured from the Byzantine Empire. The Latin Empire was intended to replace the Byzantine Empire as the Western-recognized Roman Empire in the east, with a Catholic emperor enthroned in place of the Eastern Orthodox Roman emperors. The main objective of the Latin Empire was planned by Venice, which promoted the creation of this state for their self-benefit.
Seal of Philip of Courtenay, Latin Emperor in exile 1273–1283. His title in the seal is Dei gratia imperator Romaniae et semper augustus ("By the Grace of God, Emperor of Romania, ever august").
Capture of Constantinople during the Fourth Crusade in 1204.