Vikings in Iberia
The first incursion of the Vikings in Iberia has been characterised as 'probably the most significant episode of the whole period of Viking activity in the South'. It is mentioned in "Annales Bertiniani", and dated August 844, when a group from a plundering expedition entered the Garonne and reached Galicia. Despite storm damage, some proceeded to South-West Spain. This account is consistent with several later, but independent sources in Latin and Arabic. In particular, the late ninth- or early tenth-century "Chronicle of Alfonso III" adds that after plundering a number of coastal villages they were ultimately repulsed in the vicinity of "Farum Brecantium" (i.e. the Tower of Hercules). Ramiro I of Asturias gathered troops in Galicia and Asturia for the counter-attack. After the Asturian victory, the Vikings continued their voyage in direction of Lisbon. While some authors consider that the reliability of this chronicle is open to doubt, others consider that other local chronicles confirm the arrival of the Norsemen.
Swedes
During the early stages of the Scandinavian Viking Age, Ystad in Scania and Paviken on Gotland, in present-day Sweden, were flourishing trade centres. Remains of what is believed to have been a large market have been found in Ystad dating from 600–700 AD. In Paviken, an important centre of trade in the Baltic region during the 9th and 10th centuries, remains have been found of a large Viking Age harbour with shipbuilding yards and handicraft industries. Between 800 and 1000, trade brought an abundance of silver to Gotland, and according to some scholars, the Gotlanders of this era hoarded more silver than the rest of the population of Scandinavia combined.