Chinese archeologists have identified the route of a 137-kilometer stretch of the oldest section of the Great Wall in central China's Henan Province.

The remnants of 30km of wall are still standing.

"The wall structure was built no later than 221 BC in the Warring States Period," Sun Yingmin, spokesman of the provincial Cultural Relics Bureau, said yesterday.

He said previous to this, only sporadic discoveries of wall remains were found.

The actual appearance of the main body of the Great Wall of the Chu state was only recorded in historical records. Sun said an archeological survey since 2008 led to the finding of the Great Wall structure, which runs mainly east to west.

Research in Henan proved most parts of the Great Wall of Chu were built in the Spring and Autumn Period (770-467 BC), and small parts in the Warring State Period (476-221 BC).