Archaeological excavations, undertaken in 1899 and 1932, when the area was a part of East Prussia, and in 1979, during Soviet times, suggest that a major center of Old Prussians sprang up there in the early 9th century.
Marija Gimbutas describes it as the gateway for the traffic leading to the east via the lower Nemunas basin into the lands of the Curonians, Lithuanians, and other Baltic tribes.
[2] It was superbly sited along the sand-barred shore particularly rich in amber, hidden from potential enemies within a bay "where islands, shoals, and complicated channels made the approach slow and observable".
[3] Kaup flourished as a market town protected by a garrison until the end of the 10th century, when Harald Bluetooth's son, Haakon, a Dane, raided Samland.
This attack, attested by Saxo Grammaticus, probably contributed to the downfall of Kaup, which was again burned to the ground by the Dane Cnut the Great during his anti-Prussian raid in 1016.