The sophists were traveling teachers in ancient Greece. They taught on different topics. They were great in rhetoric, and upperclass people wanted their children to learn from them. They also talked about the good life and the best way to live. Gorgias is a good example of a sophist during ancient Greece.
The people who opposed them were philosophers like Socrates and Plato. Their chief complaint was that these sophists did not teach people to be better, because these sophists did not understand philosophy, which was the only way to know that is the best way to live. Socrates complained that the sophists only sounded good, but their substance was filled with nothing else.
These sophists would continue to teach until the second century AD and beyond.