MOSCOW, September 21 (RIA Novosti) - The head of the Russian Orthodox Church on Monday held a liturgy in a church in southern Moscow to celebrate the Nativity of the Theotokos.

"This is really a military memorial of national significance," Patriarch Kirill of Moscow and All Russia said about the church on the site of an ancient monastery, which contains the relics of legendary heroes from the Battle of Kulikovo - warrior monks Alexander Peresvet and Rodion Oslyabya.

The Nativity of the Theotokos, when the birth of Mary the Mother of God is celebrated, is one of the Orthodox Church's Twelve Great Feasts.

According to church legend, Mary was born in the Galilean city of Nazareth to elderly and previously barren parents, righteous Joachim and Anna. The Archangel Gabriel told them they would give birth to a daughter named Mary through whom salvation would come to the world.

In the West, the feast is called the Nativity of Mary and is marked on September 8 due to differences in calendars used by Eastern and Western Christianity.

Russian duchies, led by the Grand Duchy of Moscow, or Muscovy, were victorious at the Battle of Kulikovo over the Tartaro-Mongols in 1380 at the Kulikovo Field (present-day Tula Region in central Russia).

The duchies fought against the Tartaro-Mongols to try and win independence from the Golden Horde and avoid paying tributes.