The Duchy of Schleswig was a duchy in Southern Jutland covering the area between about 60 km north and 70 km (45 mi) south of the current border between Germany and Denmark. The territory has been divided between the two countries since 1920, with Northern Schleswig in Denmark and Southern Schleswig in Germany. The region is also called Sleswick in English.

Danish is a North Germanic language from the Indo-European language family spoken by about six million people, principally in and around Denmark. Communities of Danish speakers are also found in Greenland, the Faroe Islands, and the northern German region of Southern Schleswig, where it has minority language status. Minor Danish-speaking communities are also found in Norway, Sweden, the United States, Canada, Brazil, and Argentina.