[4][5] The state was ruled by the Lakhmid dynasty and were generally but intermittently the allies and clients of the Sasanian Empire, and participant in the Roman–Persian Wars.

The ruling Nasrid family emerges with "Amr of the Lakhm", mentioned in the late 3rd-century Paikuli inscription among the vassals of the Sasanian Empire.

[6] This situation is exacerbated by the fact that the historical sources—mostly Byzantine—start dealing with the Lakhmids in greater detail only from the late 5th century, as well as by the relative lack of archaeological work at al-Hirah.

He then formed a large army and developed the Kingdom as a naval power, which consisted of a fleet of ships operating along the Bahraini coast.

From this position he attacked the coastal cities of Iran – which at that time was in civil war, due to a dispute as to the succession – even raiding the birthplace of the Sasanian kings, Fars province.

Imru' al-Qais escaped to Bahrain, taking his dream of a unified Arab nation with him, and then to Syria seeking the promised assistance from Constantius II which never materialized, so he stayed there until he died.

[citation needed] According to the Arab historian Abu ʿUbaidah (d. 824), Khosrow II was angry with the king, al-Nu'man III ibn al-Mundhir, for refusing to give him his daughter in marriage, and therefore imprisoned him.