Norwegian: Den første svensk-norske union(en)), was a personal union of the separate kingdoms of Sweden (which included large parts of today's Finland) and Norway together with Norway's overseas colonies (including Iceland, Greenland, the Faroe Islands and the northern isles of Orkney and Shetland).

The treaty involved the marriage of Magnus's younger sister Euphemia of Sweden to Duke Albert II of Mecklenburg as well as the promise of mutual aid in the event of an attack from Denmark.

In 1332 Scania, Blekinge and Ven were sold to the Union from Duke Johan of Holstein, after the local population expressed dissatisfaction with the Danish parliament and stated they would rather be ruled by the Swedes.

The Duke started negotiations with the Swedes and it was agreed that the Swedish king would redeem the pledge for 34,000 marks of silver (6 432 kilo).

The sum of 34,000 marks was an unheard amount at the time, and in order to raise it, the king was forced to borrow money from the church and take loans from magnates in exchange for pledges.

The king also levied extra taxes, including tolls at the Scanian fishing villages and tougher demands on the mining industry in the Bergslagen.

The nobles were also dissatisfied with the king, who had taken the national seal out of the country has not appoint a chancellor for Norway during his frequent absences abroad.

In 1339, an agreement was indeed reached with the dissatisfied Norwegians, but the dissatisfaction continued, and in 1343 Magnus' younger son Haakon VI Magnusson was elected king of Norway.

The financial crisis in the kingdom, caused by loans and pledges, gave rise to an ever-widening gap between the king and the aristocracy.

In April 1346 he sent apologies around the country, stating he was sorry for the high taxes imposed during the acquisition of Skåneland, Magnus also sent a large donation to the Birgitta Birgersdotter to establish a monastery foundation in Vadstena.

Signed in Orshek (Swedishː Nöteborg), it was the first settlement between Sweden and The Novgorod Republic regulating their border which stretched into the area known as today's Finland.

[9] As early as 1328, Sweden was encouraging settlers to take over the northern coast of the Gulf of Bothnia, which was defined by the treaty as Novgorod's possession.

The treaty did not delineate the border but rather stipulated which part of the Sami people would pay tribute to Norway and which to Novgorod, creating a kind of buffer zone in between the countries.

The answer was that if Magnus Eriksson wanted to discuss matters of faith, he had to travel to Constantinople, where Novgorod's orthodox doctrine originated.

Through negotiations and threats, King Magnus tried to get the Hansa to agree to a boycott of Novgorod in return for increased privileged trade with Visby and Livonia.

Then in 1350, he set off again with a Swedish force led by among others the knights Israel Birgersson, Lars Karlsson, Magnus Gislesson, with the men-at-arms Bengt Algotsson and Sune Håkansson, moving east to recaptured Nöteborg.

In 1354 Magnus sent an expedition to Greenland under the leadership of Pål Knutsson who owned large parts of the Tveit estate on Tysnes.

A letter from Gerard Mercator to John Dee in 1577 brings excerpts from a lost work by Jacobus Cnoyen (James Knox), which described an expedition that had traveled beyond Greenland and returned with eight men in 1364.

In 1358, Magnus Eriksson had to borrow from the money that was collected in Sweden on behalf of the papal throne, and when he could not repay this at the appointed time, both he and his pledges (several of the kingdom's nobles) were threatened with excommunication.

Dissatisfaction with the king's policies erupted in the rebellion started by Magnus Eriksson's eldest son, Erik, together with several of the kingdom's nobles in 1356.

The disagreement between them soon broke out again, and Magnus Eriksson then turned to King Valdemar in Denmark with a request for help, concluding a treaty with him in 1359.

However King Erik and his wife Beatrix died quite suddenly, probably as a result of the black death in June 1359, and Magnus Eriksson again became the sole ruler of the whole of Sweden.

This led to the formation of a large attack coalition against King Valdemar, including several Hanseatic cities, as well as Sweden and Norway.

In the winter, the situation changed completely when Haakon, probably in the hope of regaining Scania, married Valdemar's daughter, Margareta (April 1363).

Magnus Eriksson and his son could not put up any effective resistance, so that by July 1364 they held no more than Västergötland, Värmland and Dalsland in Sweden proper.

In the spring of 1365, they did seek to regain what was lost, but were defeated in March 1365 in the battle of Gataskogen, near Enköping, where Magnus Eriksson was captured.

He was in Bergen in the late autumn of 1374 when he borrowed the ship Mariabollen from Icelandic bishop Jon Skalli Eiriksson of Hólar.