HARBIN, March 31 (Xinhua) -- Archaeologists have unearthed more than 500 pieces of earthenware, stone, and bone articles that are at least 4,000 years old at a ruins in northeast China's Heilongjiang Province.

Cutting tools and containers were among the excavated items at the Honghe ruins along the Nenjiang River in the city of Qiqihar, said Zhang Wei, deputy head of the provincial cultural heritage institute.

The Neolithic ruins were initially found after local archaeologists discovered two ancient tombs, with earthenware relics unearthed between 2004 and 2009.

Many ruins sites have been found along the river, including four discovered in 2014. The largest site reaches 14 meters long.

Excavation of the ruins, which started in 2013, has overturned the previous assumption that hominid tribes in China's northeastern region had no large-scale permanent residences, said Zhang.

Ring trenches, similar to moats, were also found and are believed to have been used for defense purposes, indicating relatively high productivity, privatization, and conflicts between different tribes, Zhang said.

"These discoveries have provided evidence for the research of human activities in the late Neolithic Period in northeast China," he said.