Despite these accounts, another historian claims that Öland did not become a part of Sweden until the end of the 12th century. Until then, Öland would have been independent or possibly under the rule of Denmark or one of the kings of the Wends in present-day northern Germany. However, neither historical nor archaeological sources support these claims. Despite being located centrally in the Baltic Sea, Öland has clearly been dominated by the cultural influences from Svealand, the central part of Sweden. It is unlikely that Öland belonged to Denmark, as the Danish historian Saxo Grammaticus does not mention this in his extensive and very patriotic work about his country’s history, published around the year 1200.
The idea that Öland was independent during historic times is not very likely either. The island already prospered in the Iron Age due to its central location along the trade routes of the Baltic Sea. But prosperity and the central location also meant that Öland was exposed to widespread piracy, which was the Baltic Sea’s scourge until the 13th century. Being a long and flat island, Öland offered its inhabitants very little shelter. This is why the province has such a remarkably high concentration of ancient forts, of which Eketorp is the most famous. Öland’s population had therefore much to gain from a strong royal power able to fight off the pirates. Conversely, the strategically and economically attractive Öland would have been high on the list of areas that a ruler would want to include in his kingdom.
The most prominent trading post on Öland was Köpingsvik, and the settlement that flourished here between 750 and 1250 has been compared to Birka, near Stockholm. However, the absence of a deep-water harbour restricted further development. When Kalmar was founded on the other side of the Kalmar Strait in the late 12th century, Köpingsvik’s significance dwindled and the settlement never became a town. Near Köpingsvik, Borgholm Castle was built at the end of the 13th century. It became one of Sweden’s most important fortresses during the Middle Ages, but it was only in 1816 that Borgholm became Öland’s first and only city.
After the Håtuna games in 1306, Sweden was divided between King Birger and his two brothers, the Dukes Eric and Valdemar, in 1310. Öland was given to the Dukes and when they divided the areas between them in 1315, Valdemar became the owner of Öland and he took residence in Borgholm. Until 1356, Öland was the province that provided for Valdemar’s widow Ingeborg, who called herself “Duchess of Öland”. Denmark’s King Valdemar Atterdag conquered Öland and Gotland in 1361, but his bailiffs were killed by the local peasantry after he had left the island. During the 15th-century Union battles, Öland with Borgholm Castle was the province which remained under Union rule the longest. Eric of Pomerania lost Öland as late as 1440. Öland remained a theatre of war during the Modern Age and many sea battles were fought in its waters.
The 19th century was a more peaceful period, characterised by a dramatic increase in population. However, the agricultural crisis that started in the 1880s caused mass emigration to America. Until 1930, more than 18,000 of Öland’s inhabitants emigrated and the population decreased from 38,000 to 27,000. The island’s economy continued its decline after the period of mass emigration ended, which contributed strongly to the decision to build the Öland Bridge, which was inaugurated in 1972.