Under Caesar Augustus, the Auxilia was made up of about 250 cohort size (500 men) regiments, or a total of 125,000 men. Auxilia contained heavy infantry equipped similarly to legionaries; and almost all the army's cavalry (both armored & light), and archers and slingers. Under Severus, the total number of regiments increased to about 400 (or 250,000 men).
