, a legendary battle which supposedly took place in the 8th century, fought partly between the
Svear and
Götar There were organized political structures in Sweden before the kingdom was unified; based on archaeological evidence, early tribal societies are believed to have transitioned into organized chiefdoms in the first few centuries AD, perhaps spurred by contacts with the
Roman Empire and the rest of Europe. In the period AD 500–800, Scandinavian societies began adopting cultural elements from the newly established
Germanic kingdoms in Europe, transitioning further into
petty kingdoms. Archaeological evidence suggests that were numerous petty kingdoms throughout modern-day Sweden. Foreign sources and later native sources describe the later medieval kingdom as being composed of two main regions:
Svealand (particularly around Lake
Mälaren) and
Götaland. Sources from as early as the Roman author
Tacitus ( 56–126) mention two main peoples or tribes in modern Sweden: the
Svear (
Swedes) and
Götar (
Geats); the
Svear are mentioned in more foreign sources than the
Götar, credited with military activities at sea. The securely attested Swedish rulers in the Viking Age, predecessors of the later line of Swedish kings, ruled from the religious and political center of
Old Uppsala; though its history before the Viking Age is poorly attested, it is probable that Old Uppsala had been a political and religious center since the
Migration Period. , the center of the
protohistoric Swedish
petty kingdom which gave rise to the medieval Swedish kingdom The earliest historically attested Swedish rulers are 9th-century petty kings from the
Vita Ansgarii, an account written 870 by
Rimbert partly concerning Saint
Ansgar's visit to Svealand. Some kings of Old Uppsala are also mentioned in later Icelandic texts and sagas. The line of
legendary Swedish kings from Icelandic tradition, called
sagokungar in Swedish, are not generally treated as historical figures, though some may be based on actual chieftains or petty kings. Some later king-lists deliberately extended the sequence of kings for nationalistic purposes, such as
Johannes Magnus's
Historia de omnibus Gothorum Sueonumque regibus (1554); supposed ancient kings mentioned in such sources are clearly fictional. The petty kingdoms eventually gave rise to more complex political structures and what is today considered the beginning of the Swedish kingdom developed over the course of the
Viking Age and the subsequent
Middle Ages. For a consecutive list from then, the first Swedish king of whom anything definite is known is the 10th-century
Eric the Victorious, though the information reported about him in different sources is scarce. Eric's son
Olof Skötkonung was the first king to be baptized in Sweden and is credited with founding a Christian kingdom. The early and then medieval Swedish kingdom was an
elective monarchy, with kings being elected from particularly prominent families; this practice did however often result in
de facto dynastic succession and the formation of royal dynasties, such as those of
Eric (intermittently 1157–1250) and
Bjälbo (1250–1364) as well as infighting between rival families. From 1389 to 1523, Sweden was often united with
Denmark and
Norway under the kings of the
Kalmar Union. Sweden's full independence was restored under
Gustav I in 1523. He is often credited as the founder of modern Sweden, and in 1544 he formally abandoned the previous elective monarchy in favor of
hereditary succession. Initially adopting the medieval "King of Swedes and Geats", Gustav I later adopted the lengthier title
rex Svecorum Gothorum Vandalorumque ("king of the Swedes, Geats and
Wends"). The last monarch to be titled as king of the Swedes, Geats and Wends was
Gustaf VI Adolf () since his successor, the present king
Carl XVI Gustaf, upon his accession adopted the shortened title "King of Sweden". In 1980, the rule of succession was changed from agnatic to absolute primogeniture, to the benefit of
Princess Victoria (born 1977), the current
heir apparent. == Monarchs and regents of Sweden ==