Slav tribes in central and eastern Europe ca A.D. 600
The only region of Polish lands not affected by settlement decline and depopulation was the north-east part of the country, area occupied without interruption until the Early Medieval period by unique cultures of Baltic peoples, members of the same Indo-European family as Celts, Germans or Slavs. They became established on the south eastern coast of the Baltic, between the lower Vistula and the basin of the Western Dvina (Daugava) around 500 BC. We owe the first written references to Balts to amber. Its deposits, the richest in Europe, were on Balt territory. In AD 1st c. the Roman historian Tacitus recorded the name of the inhabitants of the land rich in amber - Aestii.
At the end of antiquity the inhabitants of north-east Poland maintained close exchange with Scandinavia as well as with western and south-east Europe. This is evidenced by the large number of imported ornaments discovered in Balt gravefields dated to this period. At that time the Balts practiced cremation and buried their dead in flat urned or pit graves (Mazury and region around Elblag) or under earth and stone barrows (Suwalki region).