The Semnones were a Germanic tribe which was settled between the Elbe and the Oder in the 1st century when they were described by Tacitus in Germania:
A grove of fetters is also mentioned in the eddic poem Helgakviða Hundingsbana II.
In the 3rd century, the Semnones shifted southwards and eventually ended up as part of the Alamanni people. An inscription found on an altar in Augsburg, a Roman monument from 260 AD, states that the Semnones were also called Juthungi.
Source: Nationalencyklopedin