Celtic tribe that invaded Greece during the first part of the 3rd century BC, finally settling east of Sirmium at the junction of the Savus and the Danube rivers. They often raided Macedonia, forcing many Roman governors there to campaign against them during the late 2nd and early 1st centuries BC. By about 12 BC, however, they appear to have submitted to Roman control, and under the empire they were given some local autonomy.