There is no such thing as the region of "Santiago". The official name is "Region Metropolitana" or Metropolitan Region, if you must.
If you accept as correct "Los Rios" (The Rivers) and "Los Lagos" (The Lakes), clearly both in spanish. Then, you should also accept as correct "Arica y Parinacota".
If you accept as correct "Los Rios" (The Rivers) and "Los Lagos" (The Lakes), clearly both in spanish. Then, you should also accept as correct "Arica y Parinacota".