By: Mir M.Hosseini
Border patrol units of the Iranian army defeated invading Avar forces that were trying to intrude the Iranian territory. Avars tried again the following year through the western coasts of the Caspian sea but they were defeated again and forced towards Europe were they galloped and ravaged until they were defeated by Charlemagne and forced to settle near Danube. Part of Iran's defense structure was the great Gorgan Wall that extended from today's Iraq borders towards north passing the Caucasia until the Indian plateau..It's construction is estimated to have begun around 5th or 6th century B.C. With castles and watchtowers that could host an army of 30,000 soldier, apart from some natural barriers, it was the only practical means to keep nomadic tribes away from farms and villages. Avars who are supposed to be relatives of Mongols or Huns had exhausted the Chinese and defeated the Heptalites, then they subdued the Slavs and established a rule in Balkans. The Roman empire had to pay them tribute to keep them silent.