Козьма Пражский
According to chronicle by Cosmas of Prague (12th century), the fortified settlement was part of early medieval Slavník's territory and etymological derives from the Slavic tribe of Dulebes, who lived there as in the mid-10th century, Al-Masudi mentioned them as Dūlāba and their "king" (ruler) as Wānjslāf (most probably Wenceslaus I, Duke of Bohemia).