Truso was a Viking Age port of trade (emporium) set up by the Scandinavians at the banks of the Nogat delta branch of the Vistula River, close to a bay (the modern Drużno lake), where it emptied into the shallow and brackish Vistula Lagoon. This sizeable lagoon is separated from the Gdańsk Bay by the Vistula Spit at the southern Baltic Sea coast. In the 9th century, the merchant Wulfstan of Hedeby travelled to Truso in the service of the English King Alfred the Great and wrote his account of the place at a prominent location of the Amber Road, which attracted merchants from central and southern Europe, who supplied the markets in the Mediterranean and the Middle East with the highly valued commodity.

The account of the voyage to the town of Truso in the land of the Pruzzens around the year 890 by Wulfstan of Hedeby has been included in Alfred the Great's translation of Orosius' Histories. Moreover, Wulfstan named Truso as being near Estmere (which is his rendition of the Old Prussian Aīstinmari and Lithuanian Aistmarės for Vistula Lagoon). In the words of Marija Gimbutas, "the name of the town is the earliest known historically in the Baltic Sea area".

Truso was situated in a central location upon the Eastern European trade routes, which led from Birka in Sweden via Visby on the island of Gotland towards the southern Baltic Sea shore, where in the 13th century the Hanseatic city of Elbing was established. From there, trade continued further south along the Amber Road to Carnuntum in the Alps. These ancient roads led further south-west and south-east to the Black Sea and eventually to North Africa and the Middle East. Gimbutas has observed that

For Old Prussia, Truso played the same central role as Haithabu for north-western Germany or the Slavic Vineta for Pomerania.

East–western trade routes lead from Truso and Wiskiauten (a rival trading centre in Old Prussia, at the south-western corner of the Courish Lagoon), along the Baltic Sea to Jutland and from there up the Slien inlet to Haithabu (Hedeby), the large trading center in Jutland. This town, located close to the modern city of Schleswig in Schleswig-Holstein, was centrally located and could be reached from all four directions over land as well as from the North Sea and the Baltic Sea.

Around the year 890, Wulfstan of Hedeby embarked on his seven-day journey from Hedeby to Truso at the behest of king Alfred the Great. He named the lands and the coasts he had passed as the ship was travelling under sail all the way. Weonodland was on his right and Langland, Laeland, Falster and Sconey on his left, all land that is subject to Denmark.

Wulfstan resumes:

Then on our left we had the land of the Burgundians, who have a king to themselves. Then, after the land of the Burgundians, we had on our left the lands that have been called from the earliest times Blekingey, and Meore, and Eowland, and Gotland, all which territory is subject to the Sweons; and Weonodland (the land of the Wends) was all the way on our right, as far as the Vistula estuary.