HOHHOT, April 17 (Xinhua) -- Remains of nine beacon towers of the Great Wall have been discovered in northern China's Inner Mongolia Autonomous Region, according to the cultural relics bureau of the Alxa League.

The beacon towers, built during the Han Dynasty (206 B.C.-220 A.D.), used to act as sophisticated milliary defense facilities along with the Great Wall during the Western Xia Dynasty (1038 A.D.-1227 A.D.), said archaeologists.

The towers, standing four km apart from each other, run from northwest to southeast in the Badain Jaran Desert and the Tengger Desert. In ancient times, the towers that connected the long walls would be ignited to alert soldiers when enemies approached.

Some of the remains of the towers are still well preserved while others are decayed rock piles.

The Alxa League in Inner Mongolia has abundant remains of the Great Wall built in the Ming, Han and Western Xia dynasties, with a total length of over 300 km.