 The absenteeism of the Italian monarch led to the rapid disappearance of a central government in the High Middle Ages, but the idea that Italy was a kingdom within the Empire remained and emperors frequently sought to impose their will on the evolving Italian city-states.The resulting wars between Guelphs and Ghibellines, the anti-imperialist and imperialist factions, respectively, were characteristic of Italian politics in the 12th–14th centuries.The Lombard League was the most famous example of this situation; though not a declared separatist movement, it openly challenged the emperor's claim to power.