The period began with the first stone tools, about 2.7 million years ago.

I don't know who else you could get to make a village out of stone tools.

Once used in the production of stone tools, the sites may be 10,000 years old.

In some early sites, stone tools are the only sign of human activity.

The age of the stone tools was no surprise, the researchers said.

At the same time, many new types of stone tools began to be produced.

The different levels within the cave show the development of stone tools.

There are also a lot of stone tools found in the cave.

Early stone tools have been discovered in various fields within the county.

Occasional stone tools remain as evidence of an early culture.