In the country between the rivers Vistula and Memel, later called East Prussia, there lived in the Middle Ages the Baltic people of the "Prußen" (Old Prussians). They worshipped nature deities, which is why they were attacked by their Christian neighbours and in the end subjugated and forcibly converted by the Teutonic Order. The only thing that was left was the later name of "Prussia".
At the time, it was a swampy, densely wooded region with most places inhabited by only a few people. The Old Prussians were loosely organised into tribes, there were no cities. Their language was similar to Lithuanian, but writing was unknown. We therefore have little knowledge about them.
They waged war with their Christian Polish neighbours. Worship of various nature deities, as also customs like polygamy, were considered despicable by Christians in those days. Early attempts at mission failed. The Teutonic Order defeated the Prussians in a long drawn-out struggle that began in 1231. Those who did not submit to baptism were killed or had to flee.
Since the Order established many settlements of mostly Low German Christians, the language and culture of the Old Prussians had disappeared by the 17th century. The names of places and waters, however, kept the memory of the Old Prussians alive for a long time.
"As they did not know God, they worshipped in their error any creature as divine, namely sun, moon and stars, thunder, birds, also quadruped animals, even the toad. They also had forests, fields and waters which they held so sacred that they did not cut wood in them, nor till fields, nor fish in them."
Illustration:
The approximate settlement areas of the various Old Prussian tribes. When the Teutonic Order began its conquests in the 13th century, the Old Prussians lived as a group of tribes without a superordinate ruler. Settlement density was very irregular, with Pomesania and the Samland being relatively densely populated.