The calculated distance (air line) between Reguengos de Monsaraz and Rio de Mouro is approximately 100 miles respectively 160 kilometers.
By car or train, the actual journey to Rio de Mouro is certainly longer, as only the direct route (as the crow flies) between Reguengos de Monsaraz and Rio de Mouro has been calculated here.
Air line (approximately)
160 kilometers
87 nautical miles