I'm not quite sure, but I seem to have found the corresponding code in minors.py
Barbarians(400, 900, {iHorseArcher: 3}, ((113, 55), (128, 62)), 9, INVADERS, target_area=((117, 46), (129, 59)), adjective="TXT_KEY_ADJECTIVE_KHITAN", promotions=(iDesertAdaptation, iSteppeAdaptation)),
Barbarians(900, 1200, {iKeshik: 2, iHorseArcher: 2}, ((105, 53), (119, 59)), 8, INVADERS, target_area=((117, 46), (129, 59)), adjective="TXT_KEY_ADJECTIVE_KHITAN", promotions=(iDesertAdaptation, iSteppeAdaptation), condition=is_free_of_civ(iTibet)),
The target areas of the two Khitan barbarians seem to be completely identical, which seems to prove my guess