Immigrants from Denmark and NW Germany arrived in Britain in the 5th and 6th Centuries A.D., speaking in related dialects belonging to the Germanic and Teutonic branches of the Indo-European language family. Today, English is most closely related to Flemish, Dutch, and German, and is somewhat related to Icelandic, Norwegian, Danish, and Swedish. Icelandic, unchanged for 1,000 years, is very close to Old English.