21 Later I went to the regions of Syria and Cilicia. -Galatians 1:21 BSB
After Paul stayed with Peter for fifteen days, see verse 18, he departed from there to preach the gospel in the Gentile regions of Syria and Cilicia. Many Gentiles came to faith in the Lord Jesus Christ.
Gentile Believers in Syria and Cilicia
22 Then the apostles and elders, with the whole church, decided to select men from among them to send to Antioch with Paul and Barnabas. They chose Judas called Barsabbas and Silas, two leaders among the brothers, 23 and sent them with this letter: The apostles and the elders, your brothers, To the brothers among the Gentiles in Antioch, Syria, and Cilicia: Greetings. -Acts 15:22-23 BSB
Paul planted many churches while preaching the gospel in those regions. Paul’s ministry was to bring people to salvation and build churches there, as churches were nonexistent. The Gentiles that got saved in those regions (Acts 15:23) were the ones who started the churches.
40 but Paul chose Silas and left, commended by the brothers to the grace of the Lord. 41 And he traveled through Syria and Cilicia, strengthening the churches. -Acts 15:40-41 BSB