Complex sentence: In the Augustan era, commanders of auxiliary units were often Roman legionary centurions, or native chieftains e.g. "ala Gallorum Atectorigiana", which was probably once commanded by a Gallic chieftain named Atectorix.
Split into simpler sentences: In the Augustan era, commanders of auxiliary units were often Roman legionary centurions, or native chieftains. For example,' was probably once commanded by a Gallic chieftain named Atectorix.