[1][2] The barony's capital was the fortress of Akova or Mattegrifon ('kill-Greek', grifon being a French term for the Greeks) built on the mountainous area known in the Chronicle of the Morea as Mesarea, separating Elis from Arcadia and dominating the upper valley of the Alpheios river, by the baronial family of de Rosières, of Burgundian origin.

[1][3] The only known baron of the barony's early period is Walter of Rosières, who is first recorded in a list of fief folders in 1228/30 and by the Chronicle as having died childless, c. 1273.

As Margaret had delayed her arrival, Prince William II of Villehardouin had already confiscated the Barony of Akova (Passavant having been lost to the Byzantines).

She then returned to Achaea, where she was imprisoned by the Angevin bailli Nicholas le Maure and died in captivity in February or March 1315.

[7][8] Five years later, in 1320, Akova along with the castles of Karytaina, Polyphengos, and Saint George in Skorta, fell to the Byzantines under Andronikos Asen.