When did beer brewing begin?

About 10,000 years ago when there were Hunter-Gatherers. (Cave men)

It was likely it was created by total accident. They left out some barley they ate for nutrients and they went to go hunt. While they were gone it rained and then the container of barley was full of water. A few weeks passed and the Hunter-Gatherers came back the container was full of 'beer' and they tried to taste it and they loved it so they made more.