After the Mongol defeat of the Hungarians, there were literally no mobilised armies against them before Paris or Rome. High density cities were of little concern to the Mongols, becuase they routinely destroyed or razed whatever they felt they would be unable to hold onto. Western Europe could not have mounted a united opposition to the Mongols as it was at war with itself. The English with the French and the Scots, Spain at war with itself and the Moors.