I just finish reading Empire Rising, ‘09 by Sam Barone; the Eskkar Saga. Other books in the series are: Dawn of Empire, Quest for Honor, Eskkar and Trella, and Battle for Empire. The Publisher is Eskkar Enterprises. This series is set in Mesopotamia during the Bronze Age in a city named Akkad. (The Bronze Age here takes place about five thousands years ago.)
In the saga, people between the rivers have begun to cease hunting and gathering in favor of living on small farms. This attracts a relentless stream of marauders. The farmers try living communally, and that necessitates a wall. Unfamiliar with building or protecting themselves, the inhabitants turn to ‘Eskkar the Barbarian’ for help.
In the beginning, they are wary of Eskkar because of his Mongol lineage. He proves himself by staving off an ancestral tribe, as he knows their battle techniques. His great value is yet to come when he creates and trains teams of infantrymen, bowman, slingers and a formidable cavalry. But what he enjoys most is out witting his enemy in battle.
When Eskkar is away on maneuvers, Akkad dwellers learn that communal living comes at a price. The city is ravaged and occupied by a brutal Egyptian and his forces. Eskkar must prove himself again. He rushes back to Akkad and at a great cost takes back the city.