Danevirke in the context of "Eckernförde"

The Danes were a North Germanic tribe inhabiting southern Scandinavia, including the area now comprising Denmark proper, northern and eastern England, and the Scanian provinces of modern-day southern Sweden, during the Nordic Iron Age and the Viking Age. They founded what became the Kingdom of Denmark. The name of their realm is believed to mean "Danish March", viz. "the march of the Danes", in Old Norse, referring to their southern border zone between the Eider and Schlei rivers, known as the Danevirke.

The terms Danish March and March of Schleswig (German: Dänische Mark or Mark Schleswig) are used to refer to a territory in modern-day Schleswig-Holstein north of the Eider and south of the Danevirke. It was established in the Early Middle Ages as a March of the Frankish Empire to defend against the Danes. The term "Danish March" is a modern designation not found in mediaeval sources. According to the Royal Frankish Annals, the Danish King led his troops "into the March" in 828 (ad marcam). In the 852 Yearbook of Fulda, there is mention of a "Guardian of the Danish Border" (custodes Danici limitis).

In Old Norse, Denmark was called Danmǫrk, viz. the marches of the Danes. The Latin name is Dania.

Thyra or Thyri (Old Norse: Þyri or Þyre) was the wife of King Gorm the Old of Denmark, and one of the first queens of Denmark believed by scholars to be historical rather than legendary. She is presented in medieval sources as a wise and powerful woman who ordered the building or fortification of the Danevirke, consistent with her commemoration on multiple Viking Age runestones. These include those at Jelling which was the seat of power for her dynasty.

Although her existence is documented in Viking Age runic inscriptions, very little is known about Thyra with certainty as no other contemporary sources about her survive. Much of her story is pieced together through 12th and 13th century sources that broadly disagree with one another, such as Icelandic sagas and writings of the medieval historians Saxo Grammaticus and Sven Aggesen. When she was born and became queen is unclear, however, she likely ruled until her death in the middle of the 10th century. Historians widely agree that she and Gorm were the parents of Harald Bluetooth and likely also Canute. The Historia Norwegiæ additionally claims that they had a daughter, Gunnhild, Mother of Kings, though this is less certain.