According to the Pomeranian chronicler, Thomas Kantzow, he was a son of the Rani king, Ratislaus of Rügen (1105−1140).
For example, they took part in 1162 in Valdemar's military campaign against Wolgast and in 1163 in the consecration of Lübeck Cathedral by Henry the Lion.
After the Danes under Valdemar I and Bishop Absalon of Roskilde conquered the Jaromarsburg in 1168, Tetzlav and Jaromar surrendered their main residence and temple site at Charenza, following negotiations, without a fight.
By recognizing the suzerainty of the Danish king and converting to Christianity, they secured their lordship over Rügen.
As vassals of the Danes, the Rani soon took part in military expeditions again against the Pomeranians, including the siege of Stettin by Valdemar I in 1170.