Eiderstedt Frisian (German: Eiderstedter Friesisch, Danish: Ejderstedfrisisk) was a dialect of the North Frisian language which was originally spoken on Eiderstedt, formerly part of the Danish Duchy of Schleswig. The Frisian language became extinct on Eiderstedt in mid-18th-Century. In contrast to the northern hundreds, Eiderstedt was economically strong and wealthy and was oriented towards the southern, Low German parts of Holstein. During the 16th century there was moreover a strong Dutch immigration.