[2] After the death of the emperor Justin I in 527, his successor Justinian I was determined to continue the war against the Sassanid Empire.

He appointed Belisarius as magister militum of the East and put him in charge of strengthening the Byzantine positions and building a new fortress near Dara to protect the region from Persian raids.

Thannuris appeared to be a convenient place for a city and a military force to be stationed but the current fort was vulnerable.

Justinian responded by reinforcing Belisarius with the duces of Phoenice Libanensis Coutzes and Bouzes, the dux of Phoenicia Proclianus (according to Malalas), Sebastianus, Vincentius, comes Basilius, some Isaurians, and Ghassanid Arabs under their king Jabalah IV ibn al-Harith (Tapharas).

He argues that the combined Byzantine army must have been superior in numbers, but the fact that Belisarius was only a dux limited his authority over other duces.

The exact course of the Persian campaign is poorly recorded in primary sources, which have often compressed the events of the battles of Thannuris and Mindouos into one.

[8] Jabalah IV ibn al-Harith, ruler of the Ghassanids, who fought under Belisarius' command as a Byzantine vassal, fell from his horse and was killed by the Persians.

[11] The Byzantine emperor Justinian sent additional troops to reinforce the border fortresses of Amida, Constantia, Edessa, Sura and Beroea.

He also raised a new army which was placed under the command of Pompeius, but a severe winter interrupted further operations until the end of the year.