Since the Eastern Han no longer maintained the post of protector general, the duty was assumed by the chief official in the course of his management of the Western Regions during the period of the Qiang's attacks towards the end of the Eastern Han dynasty in the latter part of the 2nd century CE.
[1][2] Unlike the protector general of the Western Regions, the chief official (sometimes referred to as the 'chief scribe') did not have a regular office or seat.
So in certain extent, the various statelets of Indo-European in the possession of the chief official would be under the jurisdiction of the governor of Dunhuang.
The post was roughly equal to the secondary position in support of the protector general.
It was later assumed as the protector general in 119 under the impulse of the governor of Dunhuang to disengage the leftover Xiongnu from the Western Regions.