That doesn't necessarily follow. It might simply have been the case that one region might have had a significant comparative advantage in the production of iron.
It may not necessarily follow, but it does, as there was extensive iron trade from ancient times onwards. (The Hittites gained an early advantage in the ancient arms race, because they controlled iron ore sources.)
At any rate, whether it was abundant or not, it is a resource in use since the development of iron metallurgy. Production of iron and steel is still being used as a measure of industrial production today. So I wouldm't be to quick to dismiss it as a key resource.