tetrarchy

the position, territory, or tenure of a tetrarch, especially of the ruler of the fourth part of a province or country in the ancient Roman Empire: Agrippa returned to Rome in a.d. 39 and secured the banishment of his uncle Antipas, whose tetrarchy of Galilee and Perea he was then granted.

a group of four joint rulers or chiefs, or the rule or domain of such a group: Many thanks to our tetrarchy of system administrators, who worked together to fix this complex network problem in record time.