The Harzgau was a medieval shire (Gau) in the northeastern foorhils of the Harz mountains, part of the Eastphalia region of Saxony. It included the towns of Halberstadt, Quedlinburg, and Osterwieck, and was bounded by the Oker in the west, by the Großes Bruch swamps in the north, the Bode in the east, and the Harz range in the south. The county was bordered (clockwise) by the Salzgau, the Derlingau, the Nordthüringgau, the Schwabengau, the Thuringian Helmegau, and the Liesgau. Counts in the Harzgau were: In the course of the Middle Ages the counts of Wernigerode established themselves in this region. By the 14th century, after the disintegration of the Duchy of Saxony, the Harzgau had been replaced by four smaller states: