They were presumably a confederation (comparable to the Helvetii and included the sub-tribes of the Baiocasses and the Viducasses. The Baiocasses are probably eponymous of Bayeux. Pliny mentions their capital as Augustodurus. The capital of the Viducasses was Aregenua (Vieux). They were neighours of the Aulerci.
Another tribe with the same name settled in the alpine Ubaye Valley.
Their tribal name is presumably related to the theonym Esus.