Description from Total War Fandom ::
The Bastarnae are a particularly ferocious tribe from the northern Balkans who rejoice in man-to-man combat. Some scribes would have it that there are no fiercer men of Thrace in battle, and they are a formidable resource for any Thracian commander: they are highly unlikely to break and flee from any fight. Even their weapon of choice - the rhomphaia - is a cruel looking, curved blade sharpened on the inner edge, like a sickle. With one blow, this weapon is easily capable of brutally severing an arm or leg. Each Bastarnae warrior also carries a small shield, which other than his protective, face-concealing, helmet is his only protection, not that this lack of armour worries these fearless fighters for a moment; the only concern with such battle-hungry fighters is that they are liable to fling themselves into the fray at the earliest opportunity.