According to the first century Jewish historian Josephus, Tarsus and the region that surrounds it were first populated by a grandson of Japheth named Tarshish (Antiquities of the Jews, Book 1, Chapter 6). Japheth was one of Noah's three sons who survived the great flood in the ark.
Tarsus was the cult center for the oriental pagan god Sandan (Herakles by the Greeks), who is shown riding a mythical beast (Book of Acts in Its Graeco-Roman Setting, Volume 2, by Gill and Gempf, Chapter 4).
Paul was born in Tarsus around 2 A.D. to a family who were descendants of the tribe of Benjamin and who maintained an orthodox Jewish background (Philippians 3:5 - 6). Although he was a Jew, his birth in this Roman "free city" granted him the privilege of Roman citizenship (Acts 22:28), a status that was highly sought after not only by slaves but also by those in the military.
Soon after his conversion, Paul revisited Jerusalem and was so convincing in his teaching that those who opposed the gospel wanted him killed. His presence in the city created such a stir that brethren sent him back home to Tarsus, where he stayed for four years (Summer of 36 A.D. to 40 A.D.). It seems likely that during this period he helped start a church in his hometown. He did not leave the city again until he was needed to help new believers in Syrian Antioch (Acts 9:29 - 30, 11:25 - 26).
It is noteworthy that after Paul was sent out of Jerusalem the Bible says "the churches throughout the whole of Judea and Galilee and Samaria had peace . . ." (Acts 9:31)!