I don't know, I was just never too interested in them.
Even since I started getting into history there were a few countries and races that took my attention. Obviousky it was Romania and its siblings, the Balkans, the states, and more recently the Baltics and the Caucasians. But the Celts? They never intrigued my eye. At first I didn't even knew how many Celtic people still exist. I didn't even new that Ireland was ethnically different than the UK.