Question: In pre-Roman Gaul the Belgic tribe of the Veliocasses or Velocasses controlled a large area in the lower Seine valley, which retains a trace of their name, as the Vexin, in 52 they raised 3000 men to support which son of Celtillus the Avernian, leader of the Gallic tribes?
Sentence (from "Vercingetorix"): Vercingetorix came to power after his formal designation as chieftain of the Arverni at the oppidum Gergovia in 52 BC.
Relevant evidence: No