The first written mention of Chełmno is known from a document allegedly
issued in 1065 by Duke Boleslaus II of Poland for the Benedictine monastery in
Mogilno. In 1226 Duke Konrad I of Masovia invited the Teutonic Knights to
Chełmno Land. In 1233 Kulm was granted city rights known as "Kulm
law" (renewed in 1251), the model system for over 200 Polish towns. The
town grew prosperous as a member of the mercantile Hanseatic League. Kulm and
Chelmno Land were part of the Teutonic Knights' state until 1466, when after
the Thirteen Years' War Chełmno was incorporated into Poland and made the
capital of Chełmno Voivodeship