Manglisi is a townlet in Tetritskaro municipality, on the southern slope of the Trialeti range, on the left bank of the Algeti River. Manglisi and the Manglisi valley are mentioned in the Kartlis Tskhovreba in the 4th century; Manglisi was one of the 18 principalities that independently concluded peace terms with the Arabs. By Manglisi and its valley is usually meant the territory within the following bounds: on the east, the slopes of Didgori and Mount Bender-Bendeni; on the west, the Arjevani (Kadkaia-Kachkaia) ridge and Mount Sakrisi, which the Russian-speaking population calls the Yellow Mountain; on the south, the Bender (Bedeni) ridge; and on the north, the Didgori ridge. Until 1682 there was kept at Manglisi the nail of the Cross on which, by biblical tradition, Jesus Christ was crucified. In Manglisi stands one of the most important monuments of Georgian architecture — the Manglisi church of St. Mary the Mother of God, mentioned in Georgian literature from the fourth century. In 1795, as a result of Agha Mohammad Khan's invasion, Manglisi and its district were depopulated. By 1824 the Thirteenth Erivan Grenadier Regiment was stationed at Manglisi and colonized the deserted territory.