Limitanei

Overall strategy
Unlike Peasant Levy which are undisciplined and can't be controlled directly by human players, Limitanei are pretty good by all accounts especially if facing cavalry, but suffer from attrition so they are best left at home for garrison duty. Thus they work best defensively, especially if defending settlements in the early game, but as they are levy units they will not survive in enemy territory if they encounter Attrition damage. For this reason, it is most expedient for the Byzantine player to upgrade their Limitanei forces to Akritae as soon as possible.

History
Limitanei ("borderers, border guards") became more and more of a viable force as the late Roman Empire began to face massive military challenges to its existence, first from the Persians and Germans, much later the Huns and finally the Arabs. In their earliest form, they were the remnants of the old Republican-era legio (who had been replaced by the newer comitatenses) ... and just like the same were intended to serve in the regions they were raised from. In the Caucasian east, the Limitanei in turn would soon be superseded by the Akritai.