HOHHOT, Oct. 7 (Xinhua) -- Archeologists in north China's Inner Mongolia Autonomous Region have found five sites of beacon towers dating back around 2,000 years, local cultural heritage bureau said Sunday.

Beacon towers are part of a military defense system used in ancient China to pass military signals by smoke and fire. China's well-known Great Wall features thousands of such towers.

The towers found in Inner Mongolia are believed to date back to Han Dynasty (202 B.C.- 220 A.D.) and were part of the two existing tower lines found earlier in the region, according to Li Xiaowei with local cultural heritage bureau.

"They are of great significance in studying local history and culture," said Li, adding that the bureau has rolled out plans to preserve the relics.

The towers were found during an inspection on relics in the western part of Helan Mountain in the region. Archeologists also found three sites of rock paintings dating back to Qing Dynasty (1644 A.D. to 1912 A.D.) during the trip.