During part of its existence, Jórvík had a very strong relationship with the Norse Kingdom of Dublin on Ireland. Though the two never merged, they did share four of the same kings in the form of Sigtrygg Caech, Guthfrith, Olaf and Olaf Cuaran. Also from 902 until 921, the Kingdom of Mann and the Isles was under direct Jórvík rule.
Jórvík became a flourishing small kingdom when the Danish warlord, Guthrum, headed for East Anglia, while Prince Halfdan Wide-Embrace of Sjaelland seized power in AD 876. Both were in the Danelaw, as were their English subjects. While the Danish army was busy in the British Isles, the Swedish army was occupied with defending the Danish and Swedish homelands where Halfdan's brothers were in control.
Jorvik was founded by the paternally Swedish Halfdan Ragnarsson as a Danish institution but was passed onto the Norwegians, who fought for it. Native Danish rulers who eventually made Jelling in Jutland the site of Gorm the Old's kingdom, were in the East Anglian Kingdom. The Five Burghs/Jarldoms were based upon the Kingdom of Lindsey and were a sort of frontier between each kingdom. King Canute the Great would later "reinstall" a Norwegian dynasty of jarls in Northumbria (Eric of Hlathir), with a Danish dynasty of jarls in East Anglia (Thorkel). Northern England would continue to be a source of intrigue for the Norwegians until Harald III of Norway's death at the Battle of Stamford Bridge in 1066 just prior to the Battle of Hastings and the Norman conquest.
The area of the palace built by the Viking rulers in what is now York was known as the Konungsgårthr and is today known as King's Square, which nucleates the Ainsty. New streets, lined by regular building fronts for timber houses were added to an enlarging city between AD 900 and 935, dates arrived at by tree-ring chronology carried out on remaining posts preserved in anaerobic clay subsoil.
The Viking kingdom was absorbed into England in 954, without cramping its economic success: by ca 1000, the urban boom brought the Viking city of Jórvík to a population total second only to that of London within the British Isles. William the Conqueror brought the independence of Jórvík to an end and established garrisoned castles in the city.
After the Kingdom of Jórvík was merged with Northumbria (by now an Earldom of England under the House of Wessex) the title King of Jórvík became redundant, and was succeeded by the title Earl of York, created in 960. Although some of the early Earls of York were Nordic like the Jórvík Kings, they were succeeded by Normans after the Norman conquest, until the title was abolished by King Henry II. The title Duke of York, a title of nobility in British peerage, was created in 1341, but was merged with the Crown when the 4th Duke became King Edward IV. Subsequently, the title of Duke of York has usually been given to the second son of the King or Queen.
After the excavation, the York Archaeological Trust took the decision to recreate the excavated part of Jórvík on the Coppergate site, and this is now the Jorvik Viking Centre.