Emperor Taizong's military success was, in part, a consequence of changes he initiated in the Chinese army, including improved weaponry.
Coming out of the devastation of the late Sui dynasty, Tang emperors were eager to expand their territories by conquering the Gokturks.
[4] However, the real victory came when Li Jing, regarded as one of the best generals in Chinese history, surprised the Eastern Gokturk Khan with a fast force of 3,000 Cavalry at the battle of Ying shan, which also involved a rear guard of over 100,000 Tang troops.
[6] However, Civil war and dispute in the Western Gokturks gave the Tang the opportunity to expand into Central Asia.
[11] The Battle of Talas was a military engagement between the Abbasid Caliphate and their ally, the Tibetan Empire, against the Tang dynasty under Emperor Xuanzong.
In July 751 AD, Tang and Abbasid forces met in the valley of the Talas River to vie for control of the Syr Darya region of central Asia.
In 755, the Tang dynasty was subject to the devastating Anshi Rebellion and lost much influence in Inner Asia, which came to be dominated by the Uyghurs.
Attacked on all sides, the Uyghurs retreated to the Xinjiang area and their Khanate collapsed, being replaced by the Yenisei Kyrgyz.