The hierarchical highest status among the Serer people has been those of hereditary nobles and their relatives, which meant blood links to the Mandinka conquerors. Below the nobles, came "tyeddo", or the warriors and chiefs who had helped the Mandinka rulers and paid tribute. The third status, and the largest strata came to be the "jambur", or free peasants who lacked the power of the nobles. Below the "jambur" were the artisan castes, who inherited their occupation. These castes included blacksmiths, weavers, jewelers, leatherworkers, carpenters, griots who kept the oral tradition through songs and music. Of these, all castes had a taboo in marrying a griot, and they could not be buried like others. Below the artisan castes in social status have been the slaves, who were either bought at slave markets, seized as captives, or born to a slave parent.