The Battle of the Bridge was fought between Arab Muslims led by Abu Ubaid Thaqfi, and the Persian Sasanian Empire forces led by Bahman Jaduya. It is traditionally dated to the year 634, and was the only major Persian victory over the invading Muslim armies. The new Caliph, Umar, sent Abu Ubaid to Mesopotamia to take command from Al-Muthanna. He encountered the main Persian force under Bahman Jaduya, near what is the present site of Kufa. The two forces faced each other on opposing banks of the Euphrates. As it was crossed by a bridge, the battle came to known as the Battle of the Bridge.