sentences:  According to the historian Starratt (1981), the Tuareg evolved a system of slavery that was highly differentiated.They established strata among their slaves, which determined rules as to the slave's expected behavior, marriageability, inheritance rights if any, and occupation.The "Ikelan" later became a bonded caste within Tuareg society, and they now speak the same Tamasheq language as the Tuareg nobles and share many customs.