A group of man-made cave houses dating back 5,500 years ranked top among the 10 most significant archaeological discoveries in China in 2008, the State Administration of Cultural Heritage (SACH) announced on March 31.

Other discoveries included a Bronze-Age graveyard in northwest China's Gansu Province, a tomb that proves the existence of a kingdom during the Spring and Autumn Period (770-476 BC), and a "shopping district" of the Song Dynasty (960-1279) in southwest China's Chengdu City.    

"Every discovery, chosen from 25 nominated projects, is of great and special significance in archaeological studies," said XuPingfang, a leading archaeologist with the Institute of Archaeology under the Chinese Academy of Social Sciences.

The Yangguanzhai ruin, in northwest China's Shaanxi Province, consists of 17 cave houses on a cliff and adjacent pottery kilns near Gaoling county, 20 km away from the provincial capital Xi'an.

Scientists believe the caves, built between 3,500 to 3,000 BC, were the earliest man-made cave homes in China, and belonged to a late Neolithic culture named Yangshao.

Yangshao culture originated on the middle reaches of the Yellow River and was considered a main ancestor of Chinese civilization.

Archaeologists also found pottery kilns and caves to store pottery beside the houses in Yangguangzhai, as well as pottery items, fragments and tools. They believed the caves were homes to families of pottery makers.