The legend that rice porridge was used in mortar to make robust ramparts has been verified by archaeological research in the northwestern province of Shaanxi, the state news agency Xinhua reported on Sunday. 

For centuries, rumours have circulated that even the Great Wall of China used sticky rice in their walls, to fend of hoarding invaders such as Genghis Khan.
  
Walls hard substance

During recent maintenance work on the city wall of the provincial capital Xi'an, workers found that plaster remnants on ancient bricks were quite hard to remove, said preservationist Qin Jianming.
  
A chemical test showed that the mortar reacted the same as glutinous rice to a reagent. Infra-red spectral analysis also showed that the mortar displayed a similar molecular structure to glutinous rice.
  
"Thus we can conclude that the sticky material was in the mortar," Qin was quoted as saying.
  
The use of this sticky material, Qin said, helps explain why many ancient Chinese brick structures are still standing.
  
The walls of Xi'an were built in the early years of the Ming Dynasty (1368-1644).