The most recent fossils ever found of a human-like species in southeast China have presented scientists with a mystery about what may be an unknown Stone Age culture, researchers said Wednesday.

Sometimes called the "red deer people," the remains are about 11,500 to 14,500 years old and appear to show a mix of modern and archaic peoples, said an Australian and Chinese team of researchers in the journal PLoS One.

The remains, including skulls and teeth, of at least three individuals were found in 1989 at Maludong, or Red Deer Cave, in Yunnan Province, but the fossils went unstudied until 2008.

A fourth partial skeleton was found in 1979 in a cave in the village of Longlin, in the neighboring Guangxi Zhuang Autonomous Region, but it remained encased in rock until it was eventually extracted in 2009.

"These new fossils might be of a previously unknown species, one that survived until the very end of the Ice Age around 11,000 years ago," said lead author Darren Curnoe, a professor at the University of New South Wales.

"Alternatively, they might represent a very early and previously unknown migration of modern humans out of Africa, a population who may not have contributed genetically to living people."

Most relics and remains of ancient people -- like the Neanderthals who died out some 30,000 years ago -- have been found in Europe and Africa, but fossil finds in Asia have been more rare.

Before the red deer people, no fossils younger than 100,000 years old were found in mainland East Asia, but the latest discoveries suggest the land may not have been vacant of our human-like cousins after all, the researchers said.

"The discovery of the red-deer people opens the next chapter in the human evolutionary story -- the Asian chapter -- and it's a story that's just beginning to be told," said Curnoe.