Atabek

Atabeg, Atabek, or Atabey is a hereditary title of nobility of a Turkic origin, indicating a governor of a nation or province who was subordinate to a monarch and charged with raising the crown prince. The first instance of the title's use was with early Seljuk Turks who bestowed it on the Persian vizier Nizam al-Mulk It was later used in the Kingdom of Georgia, first within the Armeno-Georgian family of Zakarid-Mxargrzeli as a military title and then within the house of Jaqeli as princes of Samtskhe.

The word atabeg is a compound of two Turkic words:ata, "ancestor", and beg or bey, "lord, leader, prince".Beg is stated in some sources as Iranian origin (as in the compound Baghdad from bag/beg and dad, "lord" given). However, according to Gerhard Doerfer, the word beg may have possibly been of Turkic origin – the origin of the word still remains disputed to this day.

The title Atabeg was common during the Seljuk rule of the Near East starting in the 12th century. It was also common in Mesopotamia (Iraq). When a Seljuk prince died, leaving minor heirs, a guardian would be appointed to protect and guide the young princes. These guardians would often marry their wards' widowed mothers, thus assuming a sort of surrogate fatherhood. Amongst the Turkmen tribes, as in Persia, the rank was senior to a khan.

...
Wikipedia