Complex sentence: The county of Périgord dates back to when the area was inhabited by the Gauls, it was home to four tribes, the name for "four tribes" in the Gaulish language was "Petrocore".
Split into simpler sentences: The county of Périgord dates back to when the area was inhabited by the Gauls. It was originally home to four tribes, the name for "four tribes" in the Gaulish language was "Petrocore".