This chapter begins with the activities of Su Lu, Khaqan of Turgesh Turks. He engaged in successive battles for about sixteen years with the Arabs on one side and with the Chinese on the other. But, after he was murdered by Baga Tarkhan (Kursul) in 738, the Turgesh Turks splitted into two parties, Black (Kara) Turgesh and Yellow Turgesh. At first, the authorities of T'ang dynasty supported the yellow party, but afterwards changed their policy and helped the black party. The battle of the Talas between the Arabs under Abbasid Caliphate and the Chinese of T'ang occurred amid the Turgesh territory in 751 after the expedition of Chinese frontier general Kao Hsien-shih to Shash (present Tashkent in Tajik SSR). However, as to the reason why the Chinese gave such a chastisement on the king of Shash, the descriptions of Chinese historians do not coincide with those of Arab chroniclers. The Chinese sources say that general Kao punished severely the king of Shash because the latter neglected the duty as a subordinate state. Ibn al-Athir, Arab historian in the 13th century, stated that the king of Farghana came into conflict with the king of Shash, the former asked for aid to the Emperor of China who sent a large force to besiege the capital of Shash and that Abu Muslim dispatched one of his generals to rescue the besieged. In my opinion, both of these records, Chinese and Arab, are not sufficient to explain the real cause of the accident. I think that Kao Hsien-shih punished the king of Shash because the latter was the most fervent helper of Yellow Turgesh, while the policy of T'ang at that time was to support the other Black Turgesh.