Complex sentence: There has been long-running controversy as to the location of Uxellodunum, but archaeological work has validated the theory that the "oppidum" was sited at Puy d'Issolu, Vayrac.
Split into simpler sentences: There has been long-running controversy as to the location of Uxellodunum. However, archaeological work has validated the theory that the "oppidum" was sited at Puy d'Issolu, Vayrac.