A pattern is emerging when one reads the articles on Celtic „wars”, „states” “conquests” and large movements of tribes.
First: Celts are the indigenous people of Europe. They live everywhere except on Mediterranean seashores where seafaring people live in their separate town kingdoms and trade along the shores. Celts live different lifestyles on different geographical territories. They are called (named) after the most characteristic occupation they pursue. Their tools and weapons vary according to their occupation. (Cattle herders, carters, horsemen, woodman, farmer, soldier, etc.) Here they are called Taurisci, Arabisci, or Scordisci, there Scythians, Sarmatians or Iaziges, or farther away Carpodaci, Bastarnae.
Second: Trading routes of trading people lead across Celtic territories. They establish trading posts in Celtic territory, where they trade with Celts. These are tolerated by the “barbarians” until the merchants accept their rules. Trading posts are then fortified against looters. Then small market towns of local people settle around trading posts. Towns are to be protected by military force which is provided by the traders. Towns are to be governed by local people with regard to the needs of the foreigners too. A mixed society with mixed lifestyle spreads around these towns.
Third: When looting along the trading route continues, the route is protected all along, and considered a border (a navigable river, a pass, etc.). Looters come from the “other side”, whoever lives there, and considered an enemy. Military garrisons and posts are established along the route on the territory of the “friendly” tribes. Military leaders and most of the soldiers come from the people of the merchants. They are not considered enemy, they are “protectors”. Local people still live under the rule of their own leader “king”, but their lifestyle and thinking is somewhat changed.
Fourth: Then the military leader with sufficient force already within the territory of Celts brings in more troops to “punish” the “looters” on the other side. Once that is settled, soldiers stay there, and a protectorate or a province is established. The king becomes a puppet king, the military leader becomes governor. But it is not obvious at first. They both issue their own similar coins.
That pattern is recognizable in every empire, in Pannonia in roman times, in Thrace’s “gradual” Macedonian occupation, and of course in America, where the same thing happened to the American Indians.
Fifth: When the occupation becomes unbearable (usually because of heavy taxes on local people) they rebel against foreign rule. First with their own forces, then when it is not successful they cry for help. They call in all the neighbouring Celtic tribes available, and with them they regain their freedom. From the point of view of the empire Celtic tribes invaded the empire. But on the Celtic side it is liberation. Therefore they live in peace with each other in a “shared” kingdom.
The roman occupation attempt on Celtic Pannonia is a good example of this pattern. Here Atilla and the Huns came for the rescue.