The Senones were a Celtic people of Gallia Celtica , who in Julius Caesars time inhabited the district which now includes the departments of Seine-et-Marne, Loiret and Yonne.

From 53-51 B.c. they were engaged in hostilities with Caesar, brought about by their expulsion of Cavarinus , whom he had appointed their king. In the last-named year a Senonian named Drappes threatened the Provincia, but was captured and starved himself to death. From this time the Gallic Senones disappear from history. In later times they were included in Gallia Lugdunensis. Their chief towns were Agedincum (later Senones, whence Sens), Metiosedum (Melun; according to A. Holder, Meudon), and Vellaunodunum (site uncertain).

See Caesar, Bell. Gall. v. 54, vii. 75, viii. 30, 44; T. R. Holmes, Caesars Conquest of Gaul (1899), pp. 482-483, 755-766, 819; A. Holder, Alkeltischer Sprachschatz, ii. (1904).

More important historically was a branch of the above (called ~vwver, Senones, by Polybius), who about 400 B.c. made their way over the Alps and, having driven out the Umbrians, settled on the east coast of Italy from Ariminum to Ancona, in the so-called ager Gallicus , and founded the town of Sena Gallica (Sinigaglia ), which became their capital. In 391 they invaded Etruria and besieged Clusium . The Clusines appealed to Rome, whose intervention, accompanied by a violation of the law of nations, led to war, the defeat of the Romans at the Allia (18 July 390) and the capture of Rome. For more than 100 years the Senones were engaged in hostilities with the Romans, until they were finally subdued (283) by P. Cornelius Dolabella and driven out of their territory. Nothing more is heard of them in Italy. It is probable that they formed part of the bands of Gauls who spread themselves over the countries by the Danube, Macedonia and Asia Minor. A Roman colony was established at Sena, called Sena Gallica to distinguish it from Sena Julia (Siena) in Etruria.

For ancient authorities see A. Holder as above; on the subjugation of the Senones by the Romans, Mommsen, Hist. of Rome (Eng. trans.), bk. ii. ch. vii.