"That's impossible!" must have been what Polish archaeologist Dariusz Manasterski said when his crew, excavating on a sandy ridge by a swampy floodplain in eastern Poland, found sherds of Bell Beaker pottery. The Beaker culture dominated western Europe at the beginning of the Bronze Age, around 2000 BC. But Beakers are rare anywhere east of Prague and almost unknown in Poland.
Map from Manasterski et al. 2020. The star marks the Supraśl Site; the dark color marks the range of the Bell Beaker culture. Not only was the Supraśl Site outside the Beaker range, it was in an area of wetlands and poor soils for farming that at the time was still dominated by hunter-gatherers of the Neman Culture (green hash marks). The site itself was surrounded by wetlands, almost an island. It is, however, accessible by boat along the nearby river, so it could conceivably have lain along a trade route. Manaterski and colleagues speculate that the site was an isolated place where religious rituals were carried out in secrecy.
The Beaker artifacts all came from four strange pit features, three of which contained cremation burials. Human bones and ash were found in patterns that suggested they had been in bags, along with carefully selected artifacts. The bags were placed in shallow pits and surrounded by more artifacts.
Outside the Beaker core area there are many sites something like this, either lone Beaker burials in areas still dominated by the local culture, or sites with eccentric mixes of Beaker and non-Beaker stuff.