Traditionally, Wolof were ruled by several powerful headmen who were from high ranking lineages based on the length of time that they resided in the area. These lineages then elected a supreme leader from a field of qualified candidates. As there were often several qualified individuals for the job, fighting often broke out between various contingents following the death of a leader. Local chiefs were usually appointed by the leader and paid their allegiance to him by maintaining order in the hinterlands and collecting taxes and tributes. Society was divided into a series of caste-like categories, and there were two categories of enslaved people, those born into the household and those who were captured or purchased.