The Collaborative International Dictionary
Phylarch \Phy"larch\, n. [L. phylarchus, Gr. ?. See Phyle, and -arch.] (Gr. Antiq.) The chief of a phyle, or tribe.
Wiktionary
n. 1 The ruler of a phyle in Ancient Greece. 2 A tribal chief, magistrate, or other local ruler. 3 Athenian hipparch, head of an Athenian clan in battle.
Wikipedia
A phylarch is a Greek title meaning "ruler of a tribe", from phyle, "tribe" + archein "to rule".
In Classical Athens, a phylarch was the elected commander of the cavalry provided by each of the city's ten tribes.
In the later Roman Empire of the 4th to 7th centuries, the title was given to the leading princes of the Empire's Arab allies in the East (essentially the equivalent to " sheikh"), both those settled within the Empire and outside. From ca. 530 to ca. 585, the individual phylarchs were subordinated to a supreme phylarch from the Ghassanid dynasty.
Usage examples of "phylarch".
The notion that the hipparch is to ride at a slower pace than his phylarchs, and to handle his horse precisely in their style, seems to me below the dignity of the office.