The Chronology of Paul's Apostleship
Galatians -

Paul's former way of life in Judaism (Gal )

Paul recognizes that "the Twelve" were apostles before he was.
Arabia was a desert region to the east of Damascus
Paul may have gone there for a time of quiet reflection and study, but his primary purpose was probably to begin carrying out his commission to preach to the Gentiles.
He must have aroused the hostility of officials in Arabia by his preaching (see 2 Corinthians ).

Paul had been preaching and teaching in the area around Damascus before he made his first visit to Jerusalem since his conversion.
The Jerusalem disciples would probably have a difficult time believing that Paul had been converted to Christ, so Barnabas provided Paul's introduction to visit privately with Peter and James (see Acts ).
Why Peter and James? In 1 Corinthians there are only two people who are mentioned by name as having Christ appear to them personally after His resurrection: Peter and James.
Paul swears an oath of accuracy for his statement. The implication is that others had given different accounts of Paul's movements during this time. In this "Galatian Chronology" Paul documents his connections with the Jerusalem apostles in order to show that his commission had not come from them, but directly from Jesus Christ Himself.

Paul's departure from Jerusalem was probably accompanied by threats on his life from his former Jewish associates (see Acts ).
He makes it clear that he did not visit the churches - he was unknown by sight to the churches of Judea.
After this first visit to Jerusalem, Paul returned to the regions of the north to continue his ministry to the Gentiles. Syria was where Damascus was situated, and Cilicia was where Paul's home town of Tarsus was located. This was clearly a region where Paul could carry out his commission to preach to the Gentiles.
It was during this time that Barnabas came to Antioch and saw the need for more in-depth teaching (Acts ). Barnabas found Paul and brought him to Antioch, where they taught the believers for at least one year. This is where Paul must have come to know Titus (an uncircumcised Gentile believer who became his missionary companion).

Paul had been ministering to the Gentiles for at least fourteen years by this time, and he had worked through many issues which had not arisen in the churches in Judea.
Paul's second visit to Jerusalem probably coincided with the "famine relief" visit that is recorded in Acts . If so, then Paul had two distinct purposes:
1. He had been asked to deliver funds to the believers in Jerusalem, and
2. He had received a revelation from Christ to discuss the gospel message and missionary activities with the apostles there.
Paul was not concerned with the validity of his gospel message, but he knew that he could not effectively carry out his mission to the Gentiles without the agreement and fellowship of the Jerusalem church. Otherwise, the cause of Christ would be divided.
Paul tells how he brought Titus with him to Jerusalem, but even though Titus was uncircumcised the authorities at Jerusalem did not compel him to be circumcised in order to be saved. Evidently the Jerusalem apostles did not have a "Circumcision Policy" - they had not seriously considered this issue because they had not yet been actively involved in ministry to Gentiles. Paul, however, had thought through the issue and knew that circumcision was not a requirement for salvation by grace through faith.

Here Paul describes certain "false brothers" who were pretending to be Christians in order to spy on the church. Some scholars believe that they were planted in the church by the Pharisees or Jewish priests in order to investigate this "threat" to Judaism.
The goal of these false brothers was to bring the believers into bondage.
kata-douloo = a Greek compound word intensifying the term for bondage.
The bondage of Law-keeping is so strong because one can never do enough to be right with God.
Paul describes how he opposed these false brothers and stood firm for the truth of the gospel.
dia-meno = another intensified compound word emphasizing a permanent condition. Paul wanted the truth to permanently remain with the believers.

Paul knew that his commission had come through a direct revelation from the resurrected Christ - the Jerusalem apostles did not further educate or commission him. He had not come to get approval for his gospel message or his authority to preach it.
The "pillars" of the church (Peter, James, and John) recognized not only that Paul's gospel was the authentic gospel, but also that his mission was to preach to the Gentiles. They gave him the right hand of fellowship. Fellowship was the real issue, and this meeting resulted in an agreement on the division of their missionary efforts - promoting fellowship and harmony in their joint mission.