Kulmerland
The first historical account of Chełmno and Chełmno Land dates back to 1065 when Bolesław II of Poland granted a tax privilege to an abbey in a nearby Mogilno. The document lists Chełmno ("Culmine") along with other towns which then belonged to the province of Masovia. The area, being closest to the Polans, came to be populated by the Lechitic Kuyavians and tribes from Greater Poland. The Masovians were led by Masos, who left the Polish duke Boleslaw I and sought refuge with the Prussians. When this area was subdued by the rulers of the Polans Chełmno became a local centre of castellany (kasztelania). Chełmno Land was Christianised in the 11th century.