According to Sacred Tradition and the history of our Church, after three days from the burial of the Most Holy Theotokos, Thomas, along with the rest of the Holy Apostles, opened up her grave and didn’t find her body. The Most Holy Theotokos revealed herself to Thomas and handed her holy belt to him as a proof of her bodily transportation to the heavens.
The One who willed to be incarnated and become human from her in his person, and to be born in the flesh he who is God the Word and Lord of Glory, and who preserved her virginity incorruptible after the birth, he was also the One that was well-pleased to honor her immaculate and spotless body, after her departure from this world, by endowing it with incorruptibility and with a transposition (metathesis) to heaven before the common, and universal resurrection.
The Holy Belt, according to tradition, was made by the Blessed Virgin Mary herself with camel hair. Originally it was kept in Jerusalem and later in Constantinople. During the reign of Emperor Arcadius (395-408), the precious Belt of the Mother of God was brought from Zela of Cappadocia to Constantinople, and placed in the Church of the Theotokos in the section of Chalcopratia. In 458 it was transferred by the Emperor Leo VI the Wise to the Blachernae church. The Empress Zoe, wife of Leo VI the Wise, out of gratitude for a miraculous cure, embroidered the Belt with gold thread, as it is found today, but divided it in three pieces. During the 12th century under Manuel I Komnenos (1143-1180) an official holiday for the Belt was established on August 31st; previously it had shared the Feast of the Vesture of the Virgin on 1 July.
A large of the Holy Belt of the Most Holy Theotokos is kept at Vatopaidi Monastery, Mount Athos.