Mangguan rock art offers clues to ancient migration

If a picture is worth a thousand words, the figurative rock paintings at the Mangguan site in Southwest China's Yunnan province carry a great many more.

Published in the Journal of Archaeological Science: Reports earlier this month, a study by researchers from the Yunnan Provincial Institute of Cultural Relics and Archaeology, Nanjing Normal University, and other institutions found that the rock paintings were created at least 4,220 years ago, based on uranium-thorium dating technology.

This makes them the oldest confirmed rock art created by a settled prehistoric community in the region. The paintings predate the rock art previously documented by researchers at the nearby Cangyuan site by more than 400 years. The Cangyuan paintings date to between about 2,700 and 3,800 years ago.

Around the same time, an abrupt climate event occurred about 4,200 years ago, causing temperatures to drop in northern China.

"The coincidence suggests that drastic climate change may have driven humans to migrate from the north to the south," Wu Yun, an associate researcher at the Yunnan Provincial Institute of Cultural Relics and Archaeology and first author of the paper, told China Daily.

Located in Gengma Dai and Va autonomous county, Lincang, the Mangguan site features red and black pigment rock paintings depicting human figures, animals, handprints and abstract signs.

Besides its well-preserved condition, Wu was particularly impressed by the use of black pigment, which is rarely seen in the rock art remains discovered in this region.

By integrating data from the three major rock art complexes of the Jinsha River Valley in Lijiang, Yunnan, Mangguan-Cangyuan in Yunnan, and the Zuojiang River in the Guangxi Zhuang autonomous region, the research team has established a chronological framework for the three stylistic phases of rock art in southwestern China.

"The first is the late Paleolithic, about 13,600 to 8,400 years ago, represented by rock art in the Jinsha River Valley featuring realistic animal motifs. The second is the late Neolithic, from about 4,200 to 2,700 years ago, represented by Mangguan-Cangyuan rock art, which shifted its focus toward human activities. The third is the early historical period, from about 1,900 to 1,700 years ago, represented by Zuojiang rock art, whose hallmark motifs are semi-squatting human figures with bent and raised arms," Wu says.

"This helps anchor the chronology of regional Cangyuan-type rock art, filling the artistic gap in the pre-Cangyuan period," she adds.

In addition to the human figure sample, the researchers also dated 11 samples taken from different motifs clustered at the Mangguan site. Their analysis showed that the paintings were created between about 3,907 and 3,056 years ago.

Because of preservation conditions and technical challenges, dating painted rock art in southwestern China has long been difficult.

The development of high-precision uranium-series dating technology in recent years has enabled Wu and her team to sample carbonate crusts covering the rock art surfaces, determine when the crusts formed and, in turn, constrain the age range of the paintings.

"Sampling only the carbonate crusts does not disturb the pigment body of the rock art, effectively protecting its integrity. Each test requires only 10 milligrams of material, making it a nearly non-destructive sampling method," Wu explains.

Wu and her team will continue to investigate the emerging chronology of rock art in the region and explore possible connections and exchanges between communities across southwestern China and neighboring areas in Southeast Asia.