During the medieval period in Europe, the dominant political system was feudalism. This hierarchical system was based on land ownership and obligations between different classes, particularly the nobility and peasantry. At the top was the king, who granted land (fiefs) to lords or barons in exchange for military service. These lords then had vassals or knights serving them, who in turn would protect the land and manage the peasants working it. This system created a tightly-knit social structure that characterized the period, influencing politics, economics, and social dynamics throughout Europe for several centuries.