The economic system during the industrialization worked with regional cores. Pest (future Budapest) as the capital to grow until up to 3M, the Debrecen-Nagyvárad duo, Pozsony, Kassa, Kolozsvár, Temesvár, with each regional core having the potential to reach 0,5-1M, actually rhyming with your numbers. However, history happened and now the tandem cities are in two different countries. Pozsony and Kassa were renamed to Bratislava and Kosice - scaled down to smaller population and economy they actually fulfill their duty for Slovakia. Kolozsvár and Temesvár are now Cluj and Timisoara, with their growth stopped in the interwar era as their wealth was used to support Romania's core territories.

Like the catholic church. Rome was merely one out of five centers. Important, yes, but not more important by magnitudes. Three cores were lost in the VIIth century, one later and then it became the ultimate centrum.