The Old English poems Widsith and Beowulf, as well as works by later Scandinavian writers (notably by Saxo Grammaticus (c. 1200)), provide some of the original written references to the Danes.
During the 10th century of the late Viking Age, the Danes officially adopted Christianity, as evidenced by several rune stones, documents and church buildings.
The new Christian influences also show in their art, jewellery and burial practices of the late Viking Age, but the transition was not rapid and definitive and older customs from the Norse religion remained to be practised to various degrees.
As Saxo's texts are the first written accounts of Denmark's history, and hence the Danes, his sources are largely surviving legends, folk lore and word of mouth.
Beginning in the 8th century, the Danes initiated the construction of trading towns across their realm, including Hedeby, Ribe, Aarhus and Viborg and expanded existing settlements such as Odense and Aalborg.
Some of the raids were followed by a gradual succession of Danish settlers and during this epoch, large areas outside Scandinavia were settled by the Danes, including the Danelaw in England and countryside and newly established towns in Ireland, the Netherlands and northern France.
In the early 11th century, King Cnut the Great (died 1035) ruled the extensive North Sea Empire for nearly 20 years, consisting of Denmark, England, Norway, southern Sweden and parts of northern Germany.
During the Viking Age, they established many coastal towns including Dublin (Dyflin), Cork, Waterford (Veðrafjǫrðr) and Limerick (Hlymrekr) and Danish settlers followed.
[7] The first Vikings appeared in Frisia, now part of the Netherlands and Germany, in 800 AD, when Danes plundered coastal settlements and later the trade town of Dorestad became a frequent target of raids.
[8] The Danes were probably involved in Frisia much earlier as Gregory of Tours (c. 538–594 AD) mentions a Danish king Chlochilaichus who was killed there while invading Frankish territory in the early 6th century.
In that year, Danes established a lasting base on Noirmoutier island, a central spot for the European salt trade at the time, and poured into the Loire Valley on larger raid expeditions.