Now when they had gone throughout Phrygia and the region of Galatia, and were forbidden of the Holy Ghost to preach the word in Asia,
Note 1 at Ac 16:6: Galatia was a province in central Asia Minor. Paul and Barnabas had ministered in Iconium, Lystra, and Derbe, all cities of Galatia, on their first missionary journey. The epistle to the Galatians was written to the believers in this area.
Note 2 at Ac 16:6: No explanation is given as to why the Holy Ghost forbade Paul and his company to preach the Word in these areas. It is certain that it was not because the Lord didn't love these people and desire their salvation. Judging from the vision that Paul had of the man in Macedonia calling for help (Ac 16:9), it can be supposed that the people of Macedonia were simply hungrier for the Gospel.
Note 3 at Ac 16:6: In Paul's time, "Asia" designated the area that would correspond to most of present-day Turkey. This was the land bounded by the Mediterranean Sea and the Black Sea and west of Galatia (see note 1 at this verse). Mysia and Bithynia were northwestern and northern portions of Asia. The seven churches that the book of Revelation was written to were in Asia (Re 1:11).