A bey is a tribal chieftain, the highest authority in a nomadic group. Beys may be semi-hereditary, but the title must generally be conferred by acclimation of the tribe, or at least its warriors or elders, upon the death or removal of the old bey. Tribes and clans often maintain their beys after entering nomadic confederacies that become longer-lived empires. If a tribe settles in a particular locale, and is given the right to administer it by an imperial authority, the beylik becomes a subordinate unit of the kingdom, analogous to a duchy or principality. Some prominent beys are brought in as advisors to a khan or other ruler, and occasionally, a ruler who grows close to an advisor may proclaim them to be a bey.