Well, these are by no means a perfect match, but the first thing that springs to mind is Copplestone's 15mm fantasy stuff. Many of the Barbarians, with blue skin and red hair, would be an OK match for the illustration you provided, although they do lack the kilts.
If 15mm is too big, then perhaps Pendraken's 10mm Gallic fanatics or warband, or their 10mm fantasy barbarians?