When is the independence of Denmark?

Unfortunately, the vikings were not very literary guys, so little is known about the establishment of a single Danish kingdom. This means that prior to the King 'Gorm the Old' (ruling in the first half of the 10th century, and it's not even 100% certain that he controlled the entire area) there is only incoherent pieces of information about various kings. It is assumed that some of the kings in preceding centuries would have had the country under control in some periods and not at other times. From this 'dark' period there are, however, several prehistorical constructions that lead historians to think that only a central power can have organised the necessary resources for their completion. Examples are the 'Danevirke' (a 15-20 km long earthen wall protecting the southern border) begun in the 7th century, and the Kanhave canal (a 500 m long canal dug through a island to give a defending ship a tactical advantage over attacking fleets) from the 8th century.

Leaving the juridical definitions, it can be pointed out that the inhabitants of what was later definitely called The Kingdom of Denmark, already centuries earlier saw themselves as a People, since early Viking settlements in France (Normady = kingdom of the Norse men) and England can have the Word 'Dane' in their names, but never the names of the subdivisions of Denmark, i.e. a Viking from Jutland (=The Danish peninsula) would called himself a Dane (at least when abroad!) rather than a Jute.