How was the government system in Gaul?

[Araujo]

The Gauls were composed by many tribes, the aquitani, arverni, aedui, sequani, etc. There were some tribes who were subdued to a direct monarchy, with a king, which was the most primitive system of government and law in the "barbarian" world. These kings had absolute power, and they could do whatever they wanted, as declaring war to any other tribe, extarminating his own people, violate any woman in the tribe, etc. But I am really curious about how were the superior councils in Gaul. Like the Aedui: that same council would elect a superior magistrate, like a roman consul, who stayed in charge with limited power but almost like a king. I don't really understand quite well the government system of those tribes. Can someone help me guys?