Please answer a question about the following article about Indigenous peoples of the Americas:

Natives of North America began practicing farming approximately 4,000 years ago, late in the Archaic period of North American cultures. Technology had advanced to the point that pottery was becoming common and the small-scale felling of trees had become feasible. Concurrently, the Archaic Indians began using fire in a controlled manner. Intentional burning of vegetation was used to mimic the effects of natural fires that tended to clear forest understories. It made travel easier and facilitated the growth of herbs and berry-producing plants, which were important for both food and medicines.

What had pottery become 4,000 years ago in the Americas?
common