Brennus (or Brennos) (d. 279 BC) was one of the leaders of the army of Gallic invasion of the Balkans, defeated the assembled Greeks at Thermopylae, and is popularly reputed to have sacked and looted Delphi, although the ancient sources do not support this. In 280 BC a great army, comprising about 85,000 warriors, coming from Pannonia and split in three divisions, marched south in a great expedition to Macedonia and central Greece. The division led by Brennus and Acichorius moved against Paionians. Some writers suppose that Brennus and Acichorius are the same person, the former being only a title and the latter the real name. The other two divisions were led by Cerethrius and by Bolgios, moving against the Thracians and Triballi, and against the Macedonians and Illyrians, respectively. Brennus is said to have belonged to an otherwise unknown tribe called the Prausi. These Gauls had settled in Pannonia because of population increases in Gaul, and sought further conquests.