The Neolithic Age is thought to have spanned from approximately 10,000 to 4,000 years ago. During this period, humans began to produce ground stone tools that were made by grinding and shaping. They also began to use clay for making pottery. A significant advancement of this period was the development of agriculture and animal husbandry, as people learned to grow crops, domesticate animals and construct permanent settlements. Neolithic sites in China are concentrated along the Yellow River and Yangtze River basin, as well as along coastal areas of Southeast China.