Ancient Picts - Pictish warriors often painted their bodies with a blue dye from a plant called "Woad". The woad would be painted in different shapes, such as animal. They were very fierce fighters, and the Romans feared them. Sometimes Celtic warriors would enter battle wearing nothing but woad and a necklace. This necklace would supposedly hold healing powers.
Roman auxiliary c.100AD. Auxilia were the non-citizen soldiers of the Empire but were recruited into the army for their local knowledge and specialist skills often as scouts, cavalry or archers. After 25 years service an auxiliary could qualify for Roman citizenship.