In the beginning of the 4th century, the Rugii moved southwards and settled at the upper Tisza in ancient Pannonia, in what is now modern Hungary.

In 453, they successfully rebelled against the Huns along with other Germanic tribes at the Battle of Nedao, after which they settled in the counties of Waldviertel and Weinviertel which lie north of the Danube.

In 476, Felethus supported the Herulian and Scirian mercenaries of Odoacer, who overthrew the Roman Emperor Romulus Augustus and made himself King of Italy.

Odoacer subsequently invaded the Kingdom of the Rugii, where he utterly defeated the Rugian troops and captured Feletheus and his wife, who were executed in Ravenna in 487.

Two years later, the Rugii joined the Ostrogothic king Theodoric the Great, who invaded Italy and defeated Odoacer in 493.