But in the 15th Century, when the Ottoman Empire invaded Georgia, this method of praying was abandoned and remained so for centuries. "We don't know why exactly the monks stopped climbing up this pillar under the Ottomans," said Tbilisi-based scholar Natia Khizanishvili, from the Korneli Kekelidze National Centre of Manuscripts. "Despite the invasion of the Ottomans, in Western Georgia, Christianity was not in danger of being abolished."