Yea I remember hearing of a "Celtic Legion" before, it was a long time ago, and from what I can remember they were very effective and were nearly the equals of their Roman counterparts in discipline, training and effectiveness. However due to the long training time and a lack of resources they werent able to be replaced very quickly unlike Rome's armies and thus met defeat. I'd always figured it was somewhere in Northern Gaul or even Souther Brittania or what not but it wouldnt be hard to believe that it was from a tribe in Asia Minor after all.