What period of time did Paul's Galatians ministry cover?

Les explains that the Galatians material covered the entire period when Paul was roaming the Roman Empire and establishing churches. During that time, Paul constantly referred to Abraham and used the allegory of Isaac and Ishmael as pictures of Law and Grace, flipping back into the Old Testament, using Jews as examples, and appealing to them to come out of blindness and legalism into the Light of God's Grace. That period ended with Acts 28, when an interruption came in Paul's ministry: he was arrested and taken to prison in Rome. After arriving in Rome following the shipwreck and turmoil from Caesarea, Paul called the chief of the Jews together after three days. He told them he had committed nothing against the people of Israel or the customs of the fathers, yet was delivered prisoner from Jerusalem into the hands of the Romans. Les notes that the Jews hated the Apostle Paul.