The name survived the collapse of Roman civil institutions in the 5th and 6th centuries, and continued to be used into modern times.
[2][3] The origin of Tiberius was obscure even in Roman times, although popular etymology sometimes connected it with the ancient city of Tibur.
A legend recorded by Livy was that the river, originally known as the Albula in Latin and the Rumon in Etruscan, came to be called Tiberis (Latin) or Thebris (Etruscan) after Tiberinus, the king of Alba Longa, was drowned in its waters.
Chase suggested that the same root may have connected the city of Tibur, the Umbrian town of Tifernum, and the mountain and river in Samnium known as Tifernus.
In any case, Tiberius was used by families of Latin, Etruscan, and Oscan origin, and was thus already distributed throughout Italy at the earliest times.