[5] According to the Stele, Alopen and his fellow missionaries came to China from Daqin (or Ta Tsin – the Byzantine Empire) in the ninth year of Emperor Taizong (Tai Tsung; 635), bringing sacred books and images.

The Church of the East mission benefited from Taizong's policy of religious tolerance, which reversed measures his father Gaozu had taken against Buddhism and other foreign religions and influences.

[5] 太宗文皇帝，光華啓運，明聖臨人，大秦國有上徳曰阿羅本，占青雲而載真經，望風律以馳艱險。貞觀九祀，至扵長安。 In the time of the accomplished Emperor Taitsung, the illustrious and magnificent founder of the dynasty, among the enlightened and holy men who arrived was the Most-virtuous Olopun, from the country of Syria.

Under Taizong's son and successor Gaozong, who continued this policy of toleration, Alopen's status expanded even further, and he was appointed bishop over the many churches built by the emperor.

[1] The story of Alopen became prominent again in the 17th century, when the Xi'an Stele was rediscovered and the Chinese were surprised to find that the "new" religion being preached by the missionaries, had actually been in existence in China more than 1,000 years earlier.