Kinsterna (Κινστέρνα) or Gisterna was a Slavic-inhabited district in the southern Peloponnese during the Late Middle Ages.
The Kinsterna is described as a fertile and rich plain northwest of the Mani Peninsula, and inhabited by Slavs, most likely the Melingoi tribe. The district was ceded by the Principality of Achaea to the Byzantine province around Mystras in 1263, but it remained largely autonomous. Thus in 1295, some of the local tribesmen captured Kalamata on their own initiative, and both the local Byzantine governor and Emperor Andronikos II Palaiologos declared themselves unable to force them to restore it to the Principality, while in the next year, the Prince of Achaea was able to recruit 200 men and a ship from among its inhabitants to fend off Byzantine attacks in Skorta.
The castles of Grand Magne and Leuktron or Beaufort were erected by the Princes of Achaea to keep the raids of the Slavs of Kinsterna at bay.