|English: Hellenic Flag of Anthimos Gazis used during the Greek War of Independence (Thessalia 1821) Greek: Σχεδίασμα σημαίας που ύψωσε ο Άνθιμος Γαζής στη Θετταλομαγνησία το 1821. (Photo credit: Wikipedia)|
In Greco-Roman antiquity, the ruler of a principality, originally the ruler of one-quarter of a region or province was known as a tetrach.
The first tetrarchs ruled the four tetrarchies of Thessaly under Philip II of Macedonia.
Ancient Thessaly or Thessalia
(Greek: Αρχαία Θεσσαλία, Thessalian: Πετθαλία, Petthalia)
It was one of the traditional regions of Ancient Greece.
During the Mycenaean period, Thessaly was known as Aeolia, a name that continued to be used for one of the major tribes of Greece, the Aeolians, and their dialect of Greek, Aeolic.
Middle English tetrarche, a Roman tetrarch, from Old French, from Late Latin tetrarcha, from Latin tetrarchēs, from Greek tetrarkhēs : tetra-, tetra- + -arkhēs, -arch.