The tribe was mentioned by the Roman historians Publius Herennius Dexippus and Ammianus Marcellinus. The meaning of their name is “descendants”, and refers to the ancient Suebian tribe of the Semnoni.
The Juthungi invaded Italy in 259–260, but on their way back they were defeated near Augsburg on 24–25 April 260 by Marcus Simplicinius Genialis (this is recorded on a Roman victory altar found in 1992). At this time the Roman Empire lost control of this part of the limes.
Between 356 and 358 the Juthungi and the Alamanni invaded the province of Raetia, and destroyed Castra Regina (Regensburg), which was the Roman capital of the province, and one of the biggest Roman military camps in south Germany, with massive stone walls and a village.
The Juthungi's eventual fate is unknown by modern historians but it is known that they cooperated with other German tribes against Rome in various wars. Due to the eventual rise of tribes such as the Franks, it is likely that the Juthungi were either absorbed by such tribes or were annihilated.