Nomarchs (Ancient Egyptian: heri-tep a'a) were Ancient Egyptian administration officials responsible of the provinces. Effectively serving as provincial governors, they each held authority over one of the 42 nomes (Egyptian: sepat) into which the country was divided. Nome is derived from the Greek nomos, meaning a province or district, and nomarch is derived from the Greek title nomarches (νομάρχης), the ruler of a nomos.
The division of the kingdom into nomes can be documented as far back as the reign of Djoser of the Third Dynasty in the early Old Kingdom, c. 2670 BCE, and probably harks even further back to the Predynastic kingdoms of the Nile valley. The earliest topographical lists of the nomes of Upper and Lower Egypt date back to the reign of Nyuserre Ini, of the mid Fifth Dynasty, from which time the nomarchs no longer lived at royal capital but stayed in their nomes.
The power of the nomarchs grew with the reforms of Nyuserre's second successor, Djedkare Isesi, which effectively decentralized the Egyptian state. The post of nomarch then quickly became hereditary, thereby creating a virtual feudal system where local allegiances slowly superseded obedience to the pharaoh. Less than 200 years after Djedkare's reign, the nomarchs had become the all-powerful heads of the provinces. At the dawn of the First Intermediate Period, the power of the pharaohs of the Seventh and Eighth Dynasties had diminished so much that they owed their position to the most powerful nomarchs, upon whom they could only bestow titles and honours. The power of the nomarchs remained important during the later royal revival under the impulse of the 11th Dynasty, originally a family of Theban nomarchs. Their power diminished during the subsequent 12th Dynasty, setting the stage for the apex of royal power during the Middle Kingdom.