When Khalid ibn Walid, after the victory at Ain Tamr, went to Arabia to the city of Domat al-Jandal, the Persians decided that he took most of his troops with him and wanted to return the territories captured by Muslims. However, Ibn Walid returned, and began to beat the Persian armies in parts. During the battle of Muzayyakh, he destroyed one of the Persian armies by night attack from three directions, and the other during the battle of Saniyi . There was only one army of Christian Arabs loyal to the Sassanids, which stood near Zumail.
Having reached Zumail a couple of days after the victory at Saniyi, Khalid ibn Walid repeated the maneuver, which had already brought him success twice. Christian Arabs were not able to resist the night attack, and tried to escape, but since the attack was conducted from three sides at the same time, this turned out to be impossible. Almost the entire army of Christian Arabs turned out to be slaughtered.
As a result of the victories of Khalid ibn Walid, the rule of the Sassanids in Iraq came to an end.