The oldest stone tools outside Africa have been discovered in western China, scientists reported on Wednesday. Made by ancient members of the human lineage, called hominins, the chipped rocks are estimated to be as much as 2.1 million years old.

The find may add a new chapter to the story of hominin evolution, suggesting that some of these species left Africa far earlier than once believed and managed to travel over 8,000 miles east of their evolutionary birthplace.

The age of the Chinese tools suggests that the hominins who made them were neither tall nor big-brained. Instead, they may have been small bipedal apes, with brains about the size of a chimpanzee’s.

“The implications of all this are large,” said Michael Petraglia, a paleoanthropologist at the Max Planck Institute for the Science of Human History, who was not involved in the new study. “We must re-evaluate our understanding of human prehistory in Eurasia.”