The calculated distance (air line) between Nāḩiyat ash Shināfīyah and Najaf is approximately 35 miles respectively 57 kilometers.
By car or train, the actual journey to Najaf is certainly longer, as only the direct route (as the crow flies) between Nāḩiyat ash Shināfīyah and Najaf has been calculated here.
Air line (approximately)
57 kilometers
31 nautical miles