The Battle of Talas

A high-altitude river valley running east-west between snow-capped mountains in the heart of Central Asia. The Talas river runs swift and grey between green meadows; the air is thin and clear; the horizon to the south is the white-blue wall of the Tian Shan range, and beyond it the Karluk steppe extends north into open country.

On the open ground on the north bank of the river, two enormous armies face one another. To the south the army of the Abbasid caliphate under Ziyad ibn Salih al-Khuza'i (rahimahu Allah), governor of Samarqand under the Abbasid governor of Khurasan Abu Muslim, black banners, the Sunni Khurasani contingents, Arab cavalry, and a great body of Persian and Soghdian regulars. To the north the army of the Tang dynasty under General Gao Xianzhi, a Goguryeo-Korean career officer of the Tang frontier, silk banners, mailed infantry, mounted archers, and an allied contingent of Karluk Turks.

The black banners of the Abbasid army are the documented colours of the new dynasty (the banner colour by which the Abbasid revolution against the Umayyads had been known, al-rayat al-sud); plain undecorated, in sharp contrast to the patterned silk standards of the Tang. The cavalry carry the lance of the Khurasani regular and the curved Central Asian sabre.

On the fifth day of contact, the Karluk Turkic contingent allied to the Tang will defect to the Muslim side; the Tang line will collapse; the Abbasid army will take a great body of Tang prisoners and seize the western edge of the Tarim basin. The day will mark the limit of Tang expansion into Central Asia and the consolidation of Muslim Sunni rule across Transoxiana and the eastern Iranian world.

The day is the eastern counterpart of Balat al-Shuhada' in the west: the Sunni Abbasid frontier defined against the Christian Franks at one end and the Tang Chinese at the other. The Sunni sources record the day as the establishment of Islam as the religion of Transoxiana, the soil from which would come the great Sunni scholars of the next generation: Imam al-Bukhari from Bukhara, Imam Muslim from Nishapur, Imam al-Tirmidhi from Tirmidh, Imam al-Nasa'i from Nasa, all born in the decades after the day.

The light is the high silver light of high summer in Central Asia. The day in the Arabic calendar is Dhul Hijja of the 133rd year after the Hijrah, corresponding to July 751 CE. The engagement extended over five days; the decisive turn was on the fifth.

In the supply train of the Abbasid army, the prisoners taken from the Tang will include, according to the later Sunni geographical tradition (al-Tha'alibi's Lata'if al-Ma'arif), craftsmen who carried the technique of papermaking westward from China; this is the conventional Sunni-tradition account of the transmission of paper from the Tang to the Islamic world, which would within a generation displace parchment as the standard medium of the great Sunni libraries of Baghdad, Cairo, and Cordoba.

The engagement is preserved on the Muslim side principally by al-Tabari (Tarikh), Ibn al-Athir (al-Kamil fi al-Tarikh), al-Tha'alibi (Lata'if al-Ma'arif), and Ibn Khaldun. On the Chinese side, by the Old Book of Tang (Jiu Tangshu) and the New Book of Tang (Xin Tangshu). The two traditions agree on the date, the place, and the consequence.

al-Tabari, Tarikh al-Rusul wa-al-Muluk (early 10th c.): The principal early Sunni historical narrative. Preserves the Khurasani Abbasid account of the campaign, the defection of the Karluks, the rout of the Tang, and the consequences.

Ibn al-Athir, al-Kamil fi al-Tarikh (early 13th c.): Sunni historical synthesis. Synthesises al-Tabari and the lost Khurasani sources on the campaign.