all the brothers with me: Paul likely wrote from Antioch of Syria. Antioch was the center of Paul’s ministry and the first hub of Gentile Christianity (see Acts 11:20–26). Paul was not alone, although his opponents in Galatia might have suggested that, but he was in fellowship with an important New Testament church.
Paul probably founded the churches of Galatia during his first missionary journey (Acts 13:4–14:26; see Galatians Book Introduction, “Recipients”).