They have historically exhibited social stratification that has included embedded castes referred to as "Higal" (or "Higalki", "Argobba"). The upper noble strata has been called "Gob" (or Asha), while the lower servile strata have been referred to as "Sáb". The three main Somali castes are called "Tumal" (sometimes spelled "Tomal"), "Midgan" and "Yibir" (sometimes spelled "Yebir"). These fell outside of the traditional clan structure. The castes have been endogamous, a person born into it inherited its occupation. The "Midgan" have been the hunters, "Tumal" were the smiths, pottery and leatherworking caste, and the "Yibir" have been the saddle and prayer mat makers and magician caste. Below the castes have been the Somali Bantus "Jareer" community, and these have been descendants of former slaves, including those who were runaway and emancipated slaves.