Battle of Jalula was fought between Sassanid Empire and Rashidun Caliphate soon after conquest of Ctesiphon. After the capturing Ctesiphon, several detachments were immediately sent to west to capture Qarqeesia and Heet the forts at the border of Byzantine empire. Still several strong Persian armies were still active in north-east of Ctesiphon at Jalula and north of Tigris at Tikrit and Mosul. The greatest threat of all was the Persian concentration at Jalula. After withdrawal from Ctesiphon, the Persian armies gathered at Jalaula north-east of Ctesiphon. Jalaula was a place of strategically importance from where routes led to Iraq, Khurasan and Azerbaijan. The Persian forces at Jalaula were commanded by General Mihran. His deputy was General Khurrazad a brother of General Rostam Farrokhzād, who commanded Persian forced at Battle of Qadisiyyah. As instructed by the Caliph Umar, Saad ibn Abi Waqqas reported all the matter to Umar. Caliph decided to deal with Jalula first, his plan was first to clear the way to north before any decisive action against Tikrit and Mosul. Umar appointed Hashim ibn Uthba to the expedition of Jalula. Some time in April 637, Hashim marched at the head of 12,000 troops from Ctesiphon and defeated Persians at Battle of Jalula, and laid siege of Jalula which lasted for seven months before surrendering to the usual terms of Jizya.