The name of Qabus ibn al-Mundhir, who had succeeded his slain brother 'Amr III ibn al-Mundhir as Lakhmid king in 569, is an Arabic form of the Persian name "Kavus", adopted under the influence of his Sassanid Persian overlords.

Not much is known of his reign except that he suffers a heavy defeat at the hands of the rival Constantinople-sponsored Ghassanid tribe under Al-Mundhir III ibn al-Harith in 570.

The succession of al-Mundhir IV ibn al-Mundhir following the death of his brother Qabus in 573 was unpopular with the inhabitants of the capital, al-Hirah, because of his violent nature and his paganism.

A Persian governor, Suhrab, had been appointed and has ruled Hirah for a year, until Zayd ibn Hammad persuades the people to accept Mundhir as their king.

The events of the reign of Al-Mundhir IV are mostly obscure, except for the sack and razing of Hirah by the Ghassanids under al-Mundhir III ibn al-Harith in 575.

The Ghassanids, who successfully oppose the Persian-oriented Lakhmids of al-Hirah, prosper economically and engage in much religious and public building; they also patronize the arts and entertain the poet Nabighah adh-Dhubyani and, later, Hassan ibn Thabit at their courts.

Subsequent Roman distrust of Ghassanid religious unorthodoxy brings down al-Harith's successors, al-Mundhir and Nu'man.

(According to one story, which seems to be supported by Nabighah's later poetry, his enemies forged a satire against Nu'man, who was so enraged that Nabighah had to leave al-Hirah in great haste.)

Nabighah moves from Jabiyah to the enemy court of the Ghassanids in Syria, where he becomes a favorite, interceding several times on behalf of his tribesmen during their wars and defeats.

He never ceases to assert his innocence to Nu'man and eventually returns to al-Hirah.

Orthodox leaders of the Eastern Roman empire, viewing the Monophysite beliefs of the the Arab Ghassanids to be unacceptably heretical, reduce Ghassan to vassal status and dispatch imperial troops to secure its borders.

Two of the wives of Lakhmid king Al-Mundhir IV ibn al-Mundhir are known by name: the Jewish captive Salma bint al-Sa'igh, the mother of his heir Nu'man, and the Christian Mariya bint al-Harith ibn Djulhum.

Mundhir is known to have had twelve or thirteen sons.

He is succeeded in 580 by his son al-Nu'man III ibn al-Mundhir (r. 580–602), the last Lakhmid king of Hirah.

Mundhir, together with his family at the capital, is treated well by Tiberius, who allows the Ghassanid king a comfortable residence and a subsidy, but denies him an audience.

Irfan Shahîd believes that this generous treatment, as well as the fact that he was not brought to trial for his supposed treason, indicate that Tiberius too did not believe the charges, but ordered the arrest chiefly to placate the strong anti-Monophysite faction in the imperial capital.

Maurice writes an encyclopedic work on the science of war (the "Strategikon"), which exercise a major influence on the military system.

Mundhir goes in the summer of 580 or 581 to Circesium on the river Euphrates, where he joins the imperial forces under the new magister militum per Orientem, Maurice, for a campaign deep into Persian territory.

The combined force moves south along the river, accompanied by a fleet of ships.

The allied army storms the fortress of Anatha and moves on until it reaches the region of Beth Aramaye in central Mesopotamia, near the Persian capital of Ctesiphon, but there they find the bridge over the Euphrates destroyed by the Persians.

With any possibility of a march to Ctesiphon gone, they are forced to retreat, especially since at the same time …

…the Persian commander Adarmahan has taken advantage of the imperial army's absence and is raiding freely in Osroene, where he sacks the provincial capital Edessa.

The retreat is arduous for the exhausted army, and Maurice and Mundhir exchange recriminations for the expedition's failure.

Mundhir and Maurice cooperate, however, in forcing Adarmahan to withdraw, and defeat him at Callinicum.

Mundhir learns upon returning to his lands that a combined Persian-Lakhmid force is preparing another attack against the Ghassanid realm.

Immediately he sets out to meet them, engages their army and comprehensively defeats it, before going on to capture the enemy camp.

It is to be his last victory.

Despite his successes, Mundhir is accused by Maurice of treason during the preceding campaign.

Maurice claims that Mundhir had revealed the imperial plan to the Persians, who then proceeded to destroy the bridge over the Euphrates.

The chronicler John of Ephesus explicitly calls this assertion a lie, as the Byzantine intentions must have been plain to the Persian commanders.

Both Maurice and Mundhir write letters to Emperor Tiberius, who tries to reconcile them.

Finally, Maurice himself visits Constantinople, where he is able to persuade Tiberius of Mundhir's guilt.

The charge of treason is almost universally dismissed by modern historians; Irfan Shahîd says that it probably had more to do with Maurice's dislike of the veteran and militarily successful Arab ruler.

This is further compounded by the Empire's habitual distrust of the "barbarian" and supposedly innately traitorous Arabs, as well as by Mundhir's staunchly Monophysite faith.

Tiberius orders Mundhir's arrest, and a trap is laid for the Ghassanid king: summoned to Constantinople to answer charges of treason, Mundhir chooses his friend, the curator Magnus, a prominent aristocratic figure and close ally to emperors Justin II and Tiberius II, as his advocate.

Magnus owns property in Evaria (present Huwwarin) and finances many of its construction projects.

Here he has built a church as well as a wall surrounding it, and now calls on Mundhir to join him and the patriarch of Antioch Gregory in the dedication ceremony.

Mundhir arrives with only a small escort and is arrested by imperial troops stationed in secret at the location.

He is transported to Constantinople, joined along the way by his wife and three of his children.

Mundhir's arrest provokes a revolt led by his four sons, especially the eldest, al-Nu'man, a man described by John of Ephesus as even more capable and warlike than his father.

Following Magnus's departure from Huwwarin, al-Nu'man's troops raid and thoroughly plunder the city, slaying a number of its residents.