The map on the right shows the Swedish empire at its height, around 1658. Note the green blob furthest to the left, below Denmark. That is the German-speaking area of Bremen-Verden. In 1611 – before the Swedish arrived, during the rule of Johann Adolf of Holstein-Gottorp – three Portuguese Jews from Amsterdam were invited to establish a sugar refinery in Bremen. Another source says that Jews were excluded until 1803.
Queen Christina of Sweden consulted the Jewish doctor, Benedict de Castro (Baruch Nehemias) (1597-1684) in 1645. He was a Sabbatean and the first identifiable Jew to visit Sweden. Christina abdicated in 1654. For a time she stayed in Antwerp with Diego Teixeira Sampayo (Abraham Senior Teixeira – part of the Teixeira de Mattos family). Before his mission to Oliver Cromwell in 1655, Menasseh Ben Israel called on her.
In the 1650s Sweden had a not very successful attempt at creating a colonial empire in West Africa, North America and the Caribbean. It is reported that a hundred years later, in 1746, the Swedes were actively soliciting (wealthy) Sephardic Jewish settlement in their country, but were rejected by the London Mahamad.
Judiska Släktforskningsföreningen i Sverige is the Jewish Genealogical Society of Sweden. There is also a Jewish Museum in Stockholm.