Battle of Oxus River
The Battle of Oxus River was a significant battle in the 7th century, fought between the Sasanian Empire and the Muslim Arab army that had overrun Persia. Following his defeat, the last Sasanian Emperor, Yazdegerd III, became a hunted fugitive who fled to Central Asia and then to China.
Prelude
was the second largest province of the Sasanian Persian Empire. It stretched from what is now north-eastern Iran, Afghanistan, and Turkmenistan. Its capital was Balkh, now in northern Afghanistan. In 651, the mission of conquering Khurasan was assigned to Ahnaf ibn Qais and Abdullah ibn Aamir. Abdullah marched from Fars and took a short and less frequent route via Rayy. Ahnaf then marched north directly to Merv, in present Turkmenistan. Merv was the capital of Khurasan, and here Yazdegerd III held his court. Upon hearing of the Muslim advance, Yazdegerd III fled to Balkh. No resistance was offered at Merv, and the Muslims occupied the capital of Khurasan without a fight.Battle
Ahnaf stayed at Merv and waited for reinforcement from Kufa. Yazdegerd proceeded to Soghd, whose ruler supplied him with a large army. Then he marched to Balkh. Ribi' b. Amir, meanwhile, retired with Kufan troops to Marw al-Rudh, where he joined al-Ahnaf.The Sasanian king, leading an army of 50,000 cavalry composed of men from Soghd, Turkestan, Balkh, and Tokharistan, arrived at Marw al-Rudh. Ahnaf had an army of 20,000 men. The two sides fought each other from morning till evening for two months at a place called Deir al-Ahnaf.
The fighting at Deir al-Ahnaf went on until Ahnaf, Yazdegerd, meanwhile, left from Marw al-Rudh to Merv, from where he took his empire's wealth and proceeded to Balkh to join the Khakan. He told his officials that he wanted to hand himself over to the protection of the Turks, but they advised him against it and asked him to seek protection from the Arabs, which he refused. He left for Turkestan while his officials took away his treasures and gave them to Ahnaf, submitting to the Arabs and being allowed to go back to their respective homes.