Complex sentence: Uar and Hunnoi are the names associated with the two biggest tribes of "Procopius's White Huns" commonly identified with the Sanskrit SvetaHuna but called Varkhon or Varkunites (OuarKhonitai) by Menander Protector.
Split into simpler sentences: Uar and Hunnoi are the names associated with the two biggest tribes of "Procopius's White Huns" commonly identified with the Sanskrit SvetaHuna. They were called Varkhon or Varkunites (OuarKhonitai) by Menander Protector.