https://elpais.com/cultura/2017/11/14/actualidad/1510672886_222840.html
New to me
One of the best-know representations of Iberian warriors. The apparent armour and the uniformity has led to the suggestion that they represent auxiliaries in Punic or Roman service.
The artists lack of skill (see brain explosion when confronted with a horse rider with two legs) might impede inference?
Either that or Spanish cavalry really did ride sidesaddle, at least in some situations.
I would suggest that whatever the apparent or real anatomical deficiencies, the uniformity of equipment does suggest uniform equipment. Noteworthy is the differentiation of a single figure with a crested helmet, perhaps an officer, and the right-facing infantry bearing javelin in one hand and falcata in the other while their opponents have javelin in one hand and shield in the other. One may note also the different styles of armour despite identical shields.
I would be very tempted to associate this decoration with the battle of Castulo (https://en.wikipedia.org/wiki/Battle_of_the_Upper_Baetis#Battle_of_Castulo) in 211 BC. This is of course just one possibility; there are many others.