Anglia (German and Low German: Angeln; Danish and South Jutlandic: Angel; Engel) is a small peninsula on the eastern coast of Jutland (the Cimbric Peninsula). Jutland consists of the mainland of Denmark and the northernmost German state of Schleswig-Holstein. Anglia belongs to the region of Southern Schleswig, which constitutes the northern part of Schleswig-Holstein, and protrudes into the Bay of Kiel of the Baltic Sea.
To the south, Anglia is separated from the neighbouring peninsula of Swania (Ger. Schwansen, Dan. Svans or Svansø) by the Sly Firth (Ger. Schlei, Dan. Sli), and to the north from the Danish peninsula of Sundeved (Ger. Sundewitt) and the Danish island of Als (Ger. Alsen) by the Flensburg Firth (Ger. Flensburger Förde, Dan. Flensborg Fjord). The landscape is hilly, dotted with numerous lakes. Whether ancient Anglia conformed to the borders of the Anglian Peninsula is uncertain. It may have been somewhat larger; however, the ancient sources mainly concur that it also included the peninsula's territory.
Anglia has a significance far beyond its current small area and country terrain, in that it is believed to have been the original home of the Angles, Germanic settlers in East Anglia, Central and Northern England, and the Eastern Scottish Lowlands. Their migration led to their new homeland being named after them, from which the name "England" derives. England, East, Mid and West Anglia as well as the English language, thus, ultimately derive at least their names from Anglia.
Glücksburg Castle in Glücksburg in the north of Anglia, is the seat of the House of Schleswig-Holstein-Sonderburg-Glücksburg, of which the king of the United Kingdom is a patrilineal member.
The German word Angeln has been hypothesised to originate from the Germanic Proto-Indo-European root , meaning "narrow", meaning here "the Narrow [Water]", i.e. the Sly Firth; the root would be , "tight" (compare Ger. and Dutch eng = "narrow", "England" = Ger. England, "narrow land" = Ger. enges Land).