Allagion

The allagion (Greek: ἀλλάγιον) was a Byzantine military term designating a military unit. It first appeared in the mid-to-late 10th century, and by the 13th century had become the most frequent term used for the Byzantine army's standing regiments, persisting until the late 14th century.

The term means "rotation of duties", and first appears in the latter half of the 10th century as an alternate term for a cavalry bandon, numbering between 50 and 400 men. In the 10th and 11th centuries, provincial allagia had some 50–150 men, while those of the central imperial army were closer to the upper limit, with circa 320–400 men.