The shores of Ruppiner See were settled since the Stone Age; in the 9th century AD, Poggenwerder Island was the site of a Slavic gord (burgwall), probably built by Polabian Zamizi tribes. The castle was possibly slighted during the Wendish Crusade of 1147 and about 1200 a lowland castle was erected on an opposite peninsula, which from 1214 served as the residence of the Lords of Ruppin. Their lordship remained an immediate Imperial estate until its final incorporation into the neighbouring Margraviate of Brandenburg in 1524.