The Nantuates or Nantuatae were an ancient people of modern-day Switzerland, whose territory extended into adjacent areas now in modern-day France.
At Roman contact, the Nantuates bordered on the Allobroges and in Julius Caesar's time were included within the limits of the Provincia. Caesar at the close of the campaign of 57 BCE sent Servius Galba with some troops into the country of the Nantuates, Veragri and Seduni, who extend from the borders of the Allobroges, the Lacus Lemannus (modern Lake Geneva) and the river Rhone to the summits of the Alps. The position of the Seduni in the valley of the Rhone about Sion, and of the Veragri lower down at Martigny, being ascertained, the Nantuates were likely located in the Chablais, on the south side of Lake Geneva, a position which is conformable to Caesar's text. Strabo (iv.) who probably got his information from Caesar's work, speaks of the Veragri, Nantuatae, and the Leman lake; from which we might infer that the Nantuates were near the lake. An inscription in honor of Augustus, which according to Guichenon's testimony was found at Saint-Maurice-en-Valais, which is in the canton of Valais lower down than Martigny, contains the words Nantuates patrono; and if the inscription belongs to the spot where it is found, it is some evidence that the Nantuates were in the lower part of the Valais. But if the Nantuates were neighbors of the Allobroges, they must have extended westward along the south bank of the lake into the Chablais. The Chablais is that part of Savoy which lies along the Leman lake between the Arve and the Valais. It is not certain how far the Allobroges extended along the Leman lake east of Geneva, which town was in their territory. It has been observed that the word nanto- in the Celtic language signifies 'valley, stream, running water'; and it is said that in the dialect of Savoy, every little mountain stream is called Nant, and that there are many streams of this name. Nant is also a Welsh word for 'stream'.