The calculated distance (air line) between Al Mishkhāb and Ar Rumaythah is approximately 46 miles respectively 74 kilometers.
By car or train, the actual journey to Ar Rumaythah is certainly longer, as only the direct route (as the crow flies) between Al Mishkhāb and Ar Rumaythah has been calculated here.
Air line (approximately)
74 kilometers
40 nautical miles