after his cousin wartislaw iii had formally accepted the brandenburg overlordship by the 1236 treaty of kremmen, duke barnim i came to terms with the mighty ascanian margraves in the 1250 treaty of landin: he confessed himself a brandenburg vassal and had to renounce the uckermark region, nevertheless he reached the consent, that the fief of his cousin wartislaw would remain with the griffin dynasty upon his death. when duke wartislaw iii died in 1264, barnim i was able to unite the whole duchy of pomerania under his rule. he promoted the "ostsiedlung" by introducing german settlers and customs into the duchy, established many towns, among them prenzlau, szczecin, gartz, anklam, stargard, gryfino, police, pyrzyce, ueckermünde and goleniów. he was also known for his generous ecclesiastical foundations, and supported the extension of the secular reign of the cammin bishops in the kołobrzeg area.