The origin of Denmark is lost in prehistory. Prior to being populated by Scandinavians, Denmark was home to Celts - as evidenced by the discovery of ritualistic bog murders and burials. The oldest Danevirke is from the 7th century, at the same time as the new Runic alphabet.
Up into the 11th century the Danes were known as Vikings, together with Norwegians and Swedes, colonising, raiding and trading in all parts of Europe. Many archaeologists and historians believe that the Viking even made it as far as America. They traveled from Scandinavia to Iceland, then further to Greenland and then finally America.
At various times Denmark has ruled parts of England and Ireland, Norway, Sweden, Finland, Iceland and parts of the Virgin Islands, Tranquebar in India, parts of the Baltic coast and what is now northern Germany. Scania, Blekinge and Halland were part of Denmark for most of its early history, but were lost to Sweden in 1658. The union with Norway was dissolved in 1814, when Norway entered a new union with Sweden (until 1905).
The Danish liberal and national movement gained momentum in the 1830s, and after the European revolutions of 1848 Denmark became a constitutional monarchy June 5, 1849.
After the Second War of Schleswig (Danish: Slesvig) in 1864 Denmark was forced to cede Schleswig-Holstein to Prussia, in a defeat that left deep marks in the Danish national identity. After this point Denmark adopted a policy of neutrality, following which Denmark stayed neutral in World War I. Following the defeat of Germany Denmark was offered by the Versailles powers the return of Schleswig-Holstein. Fearing German irridentism Denmark refused to consider the return of Holstein and insisted on a plebiscite concerning the return of Schleswig. In 1920, following the plebiscite, Northern Schleswig was recovered by Denmark.