Egyptian archaeologists have found what they believe might be the oldest human footprint in history. They discovered the footprint, imprinted on mud and then hardened into rock, while exploring a prehistoric site in Siwa, a desert oasis in the west of the country.

“This could go back about two million years,” speculated the head of Egypt’s antiquities council, Zahi Hawass. “It could be the most important discovery in Egypt.”

Previously, the earliest human archaeological evidence from Egypt dated back around 200,000 years, Reuters reports.

Archaeologists said it is even possible that the footprint could date back further than the 3.2 million year-old fossil Lucy, the partial skeleton of an ape-man, which was unearthed in Ethiopia in 1974.