Christian truth." However, to date, there is little to no archaeological evidence or knowledge about the pre-Church-of-the-East classical Chinese and/or Tocharian church. Two (possibly Church of the East) monks were preaching Christianity in India in the 6th century before they smuggled silkworm eggs from China to the Byzantine Empire. The first documentation of Christianity entering China was written on an 8th-century stone tablet known as the Xi'an Stele. It records that Christians reached the Tang dynasty capital Xi'an in 635 and were allowed to establish places of worship and to propagate their faith. The leader of the Christian travelers was Alopen. Some modern scholars question whether Nestorianism is the proper term for the Christianity that was practiced in China, since it did not adhere to what was preached by Nestorius. They instead prefer to refer to it as "Church of the East", a term which encompasses the various forms of early Christianity in Asia. In 845, at the height of the Great Anti-Buddhist Persecution, the Emperor Wuzong of Tang decreed that Buddhism, Christianity, and Zoroastrianism be banned, and their very considerable assets forfeited to the state. In 986 a monk reported to the Patriarch of the East: Christianity is extinct in China; the native Christians have perished in one way or another; the church has been destroyed and there is only one Christian left in the land. Karel Pieters noted that some Christian gravestones are dated from the Song and Liao dynasties (ca. 900s to 1200s), implying that some Christians remained in China in these eras. Medieval period Christianity was a major influence in the Mongol Empire, as several Mongol tribes were primarily Church of the East Christian, and many of the wives of Genghis Khan's descendants were Christian. Contacts with Western Christianity also came in this time period, via envoys from the Papacy to the capital of the Yuan dynasty in Khanbaliq (present-day Beijing). Church of the East Christianity was well established in China, as is attested by the monks Rabban Bar Sauma and Rabban Marcos, both of whom made a famous pilgrimage to the West, visiting many Church of the East communities along the way. Marcos was elected as Patriarch of the Church of the East, and Bar Sauma went as far as visiting the courts of Europe in 1287–1288, where he told Western monarchs about Christianity among the Mongols. In 1294, Franciscan friars from Europe initiated mission