After Demetrius’ defeat at Gaza in 312 B.C. Seleucus rushed with a few soldiers to his old satrapy of Babylon, on the way he recruited some soldiers, possibly Silver Shields at Harran, and resumed his advance to retake Babylon. Hearing of this news Nicanor, satrap of the east under Antigonus, quickly assembled an army composed of 10,000 infantry and 7,000 cavalry, with a large contingent under Eaugoras, satrap of Persia, and possibly the remaining Silver Shields who Antigonus had exiled to Arachosia in 316 BC. After assembling his army he marched west, towards Seleucus who could gather no more than 3,400 soldiers, the majority of them infantry, so he decided to shadow Nicanor's movements and waited for him to cross the Tigris hiding in the marshy terrain around it.