The answer is reunification under the Eleventh Dynasty after
period of defragmentation did rulers of Egypt accomplish during the Middle
Kingdom. When the Eleventh Dynasty reunified Egypt it had to create a central
administration such as had not occurred in Egypt since the downfall of the Old
Kingdom government. To do this, it chosen people to positions which had fallen
out of use in the decentralized First Intermediate Period. Highest among these
was the Vizier.
