Ala meaning literally “wing” was a Roman military term, originally meaning only the wing formation combat.
During the Roman Republic, ala consisted of allied infantry in the strength of a legion divided into cohorts and cavalry of 300 soldiers.
During the Roman Empire, between the 1st and 4th centuries CE, ala it was an independent unit of Roman cavalry. There were then: ala thousandth (ala milliariae) consisting of about 1,000 riders divided into 24 turmae 42 riders each, and ala five hundred (ala quinquenariae) with approximately 500 riders divided into 16 turmae of 30 riders.
The term ala also meant any units of auxiliary troops.
