A team of Japanese archaeologists claim to have unearthed the oldest stone tools in Japan —— 20 artifacts dating back some 120,000 years —— in Izumo, Shimane Prefecture.

The discovery has suggested humans existed here long before 40,000 years ago as currently thought by researchers.

The excavation team, led by Doshisha University professor Kazuto Matsufuji, found the stone tools measuring between 1.5 cm and 5.2 cm about 2 meters below ground. They were found in a soil layer sandwiched between layers from around 127,000 years ago and 110,000 years ago.

One of the stone implements from the Sunabara remains has a sharp edge that Prof. Matsufuji said is an artifact that could have been used in a thrusting object.

The findings may pave the way for a review of the history of ancient mankind in Japan and give an impetus to research on the Paleolithic Period.

The basic assumption among researchers has been that the first human ancestors landed in Japan about 40,000 years ago.

In August, Toshiro Naruse, a professor emeritus at Hyogo University of Teacher Education, discovered the first of the 20 stone tools in a slope and Prof. Matsufuji and other researchers joined Prof. Naruse the following month and uncovered the other objects around the area.