Complex sentence: A settlement is likely to have existed at the site of Alba before the "civitas" of the Helvii came under Roman rule, and there are indications of an early oppidum near the Chaulène plateau, northwest of Alba.
Split into simpler sentences: A settlement is likely to have existed at the site of Alba before the "civitas" of the Helvii came under Roman rule. There are indications of an early oppidum near the Chaulène plateau, northwest of Alba.