Lakhmia, also known as the Kingdom of the Banu Lakhm, was an ancient kingdom in the northern part of the Arabian Peninsula with its capital at al-Hirah. The Lakhmids were an Arab tribe who migrated from Yemen in the late second century and set up their state on the southern banks of the Euphrate. For many years they were vassals of the Sassanid Persians, acting as a buffer between Mesopotamia and the tribes of the desert, until they were annexed in 602 by Khusrau II.
In 633 Lakhmia revolted against Persian rule and threw its lot in with the newly-founded Talibid Caliphate. The Persians retaliated with all their might, and the Lakhmids sent messages pleading with Caliph Ali for assistance. General Khalid ibn al-Walid was sent with an army to relieve the besieged Lakhmids, provoking war between the Caliphate and the Persian Empire.
After the Persians were defeated the Lakhmids converted en masse to Islam and joined with the Caliphate. From then on their history is shared with Arabia as a whole, though for a long time they retained a distinct identity. Several families descended from the Beni Lakhm are still prominent in Oman and Nejd to this day.