What is "dithmarschen"

Dithmarschen (, Low Saxon pronunciation: , archaic in English: Ditmarsh, Danish: Ditmarsken, Middle Latin: Tedmarsgo) is a district in Schleswig-Holstein, Germany. It is bounded by (from the north and clockwise) the districts of Nordfriesland, Schleswig-Flensburg, Rendsburg-Eckernförde, and Steinburg, by the state of Lower Saxony (district of Stade, from which it is separated by the Elbe river), and by the North Sea.