Feudalism offered fiefs the opportunity to have access to lands that could be used for food production or manufacturing. These land grants were solely at the discretion of the monarch, and were given in exchange for fealty and a specified amount of tribute. Fiefs were one of the three major tiers of classic feudalism, beginning with lords (nobles), who controlled a number of vassals (those who relied on the nobles for a sustained living), and finally fiefs (people who managed production and use of land). This system of patronage was often extremely unstable and given to shifting alliances between the Crown and the nobility.