The Tectosages, the Trocmii, and Tolistobogii, as fierce as they were, fought and will fight for centuries their neihgbours, starting with the Hennelistic power that was pergamum in the west. But no only. This section is about all the surrounding kingdoms and empires and their armies around.
The Galatian's Friends and Adversaries
The Galatians were fierce warriors of Celtic origin, and although their exact starting point in still subject to debate, they retained celtic/gallic armament, tactics and organization. Their equipment however changed over time, as they acquired enemi's equipments, notably helmets, shields and swords, body armour and everything in between.
As mercenaries, they started to change their tactics as well, fighting about notably the Seleucids or Ptolemies. As lavishly rewarded "seel swords" and considered very seriously by these Hellenistc powers, their attire started to even blend more with Hellenistic style, to the point of late Galatian "Katoikai" mercenaries, had tunics, sandals, greek kopis swords and Thueros shields, as shown in many depictions as well as masked helmets a bit like for the Romans hide their "barbarian face".
Splendid example of cross-culture in the IVth Century BC, the Agris ceremonial helmet of the era, widely decorated in Greek and Celtic patterns. The Galatians helmets of chieftains or nobles were probably inspired by ths style, with even some persian inputs. Sadly, we cannot find today any artefact confirming Galatian's headgear in 280-50 BC.