Danish history dates back to the Viking Age, around the 8th to 11th centuries, when the Vikings from Denmark explored and settled in various parts of Europe. They were known for their seafaring skills and established trade routes, influencing cultures across the continent. The unification of Denmark began in the 10th century under King Harald Bluetooth, who converted the country to Christianity. In the following centuries, Denmark became a significant power in Northern Europe, forming the Kalmar Union with Norway and Sweden in the late 14th century. The country faced various conflicts, including the Danish-Swedish Wars, and underwent significant changes during the Reformation in the 16th century, leading to the establishment of a Lutheran state.