The Banu Lakhm were an Arab tribe who had founded a kingdom on the southern banks of the Euphrates, with its capital at Al-Hira. For a long time vassals of Persia, in 602 they had unsuccessfully revolted, resulting in the destruction of the kingdom and its annexation to Persia. Many Lakhmid Arabs however remained in the area, chafing under Persian rule, and Ali thought that he could incite them to rebel and join with the Caliphate.