The first recorded Christian mission to China was led by the Syriac monk known in Chinese as Alopen. Alopen's mission arrived in the Chinese capital Chang'an in 635, during the reign of Emperor Taizong of the Tang Dynasty. Taizong extended official tolerance to the mission and invited the Christians to translate their sacred works for the imperial library. This tolerance was followed by many of Taizong's successors, allowing the Church of the East to thrive in China for over 200 years.