Danish Census Book
"Thy" is originally the same word as Old Norse "þjóð" ("thioth"), meaning people. The Danish Census Book of King Valdemar II of 1231 mentions "Thiuthæsysæl", i.e. the syssel of Thy. Thy is by some scholars thought to be the origin of the Teutons; Ptolemy placed the Teutons and the Cimbri at the northern end of Jutland on his ancient map.