Paul's life was becoming that of a fugitive: escaping from Damascus in a basket, then being hustled out of Jerusalem. He went to Tarsus, according to Acts, and then some time later to Antioch (9.30; 11.26). Galatians agrees with this (1.21). Actually it says that he went to Syria (whose capital was Antioch) and to Cilicia (where Tarsus was), which could mean that he went to Tarsus via Syria. But more likely Paul mentions Syria first because it is what happened there, in Antioch, that is going to be the focus of his attention (in Galatians 2).
It makes sense that Paul should return to Tarsus. He could hope to find some refuge in his home town. It was also a place where he might have wanted to go and share his new faith in the Messiah, Jesus. How welcome he will have been is another question; presumably some of his friends and family will have been very angry at his change of religious direction. We have no definite information about what he did when he got to Tarsus. He may have kept a very low profile. But it is hard to imagine him going home and not seeking to share his new faith in the synagogue circles where he grew up. Acts 15.41 speaks of Paul strengthening the churches of Syria and Cilicia, which may suggest that he did establish a church or churches in the Tarsus area. We don't know whether he developed a mission to Gentiles or how long he stayed there. Maybe it was not very long.
What we do know is that he moved on to Antioch in Syria. Acts tells us this directly (11.25, 26), and Galatians suggests the same (1.21, 2.11).
Syrian Antioch – to be distinguished from Pisidian Antioch in central Turkey – is modern Antakya, and was a very important city in New Testament times. It was the capital of the Roman province of Syria, and effectively the capital of the eastern part of the Roman Empire. It was variously described as 'the third city of the empire', 'the queen of the East', and 'Antioch the beautiful'. The senior