The interpretation timeline
Galatians 1:21 Douay-Rheims

Afterwards I came into the regions of Syria and Cilicia.

A.D. 407 – 1871 5 witnesses

Patristic

before A.D. 750
407
A.D.
John Chrysostom Patristic
A.D. 347–407
“"Then I came into the regions of Syria and Cilicia." After his interview with Peter, he resumes his preaching and the task which lay before him, avoiding Judaea, both because of his mission being to the Gentiles, and of his unwillingness to "build upon another man's foundation." Wherefore there was not even a chance meeting, as appears from what follows.”
Source

Scholastic

c. 1100 – 1500
1273
A.D.
Thomas Aquinas Catholic
1225–1274
“After the Apostle has above shown that he did not receive the Gospel from man before his conversion, nor at the time of his conversion, here he proves that he did not receive it from man even after his conversion; rather, here he shows how his teaching was approved by men. And concerning this he does two things. First, he shows how his teaching was approved by the apostles; second, he shows how it was approved by the other faithful, at the place then I came into the regions, etc. And first he narrates the fact; second he confirms the truth of what he has said, at the place behold, before God, etc. He says therefore: although I did not go to the apostles in order to be instructed by them concerning the beginning of my conversion, since I was already instructed by Christ, nevertheless, driven by an affection of charity, after three years — namely, of my conversion — I came to Jerusalem, since I had for a long time desired to see Peter, not in order to learn from him, but in order to visit him. Job 5:24: "visiting your beauty," etc. And I remained with him fifteen days, being found by him to be a truthful apostle. And he says fifteen days, because this number is composed of eight and seven. Now the number eight is the number of the New Testament, in which the eighth day of those who rise again is awaited; while the number seven is the number of the Old Testament, because it celebrates the seventh day. He remained with Peter fifteen days, conferring with him about the mysteries of the Old and New Testament. And lest it be believed that, although he was not instructed by Peter, he was nevertheless instructed by others, he adds that he was not instructed by others either. Hence he says but of the other apostles I saw none, that is, no one, by whom I might have been instructed, except James the brother of the Lord. For he saw him in Jerusalem. Concerning this James it should be known that he was bishop of Jerusalem, and was called James the Less, because he had been called after the other James. Many things are said about him at Acts 15:13ff. He also wrote a canonical epistle. But why he is called the brother of the Lord is said differently by different people. For Helvidius says that he is called brother of the Lord for this reason, that he was the son of the Blessed Virgin. For he says that the Blessed Virgin conceived and bore Christ, and after the birth of Christ conceived by Joseph, and bore other sons. But this error has been condemned and rejected. Likewise it is plainly false, because James was not the son of Joseph, but of Alphaeus. Others, however, say that Joseph, before the Blessed Virgin, had another wife, from whom he had a son James and others, and when she died, he took the Blessed Virgin as wife, from whom Christ was born, yet not known by Joseph, but by the Holy Spirit, as is said in the Gospel. Because, then, kinships are named from the father, and Joseph was thought to be the father of Christ, therefore this James, although he was not the son of the Virgin, was nevertheless called brother of the Lord. But this is false, because if the Lord did not wish his mother, a virgin, to be entrusted to the keeping of anyone but a virgin, how would he have permitted her spouse not to have been a virgin, and to have remained so? Therefore others say, and it is touched on in the Gloss, that this James was the son of Mary of Cleophas, who was the sister of the Virgin. For they say that Anna, the mother of the Blessed Virgin, married first Joachim, from whom she bore Mary, the mother of the Lord; when he died, she married Cleophas, the brother of Joachim, from whom she bore Mary of Cleophas, and from her was born James the Less, Jude, and Simon; when he died, it is said that she then married a certain third man, who was called Salome, from whom she conceived and bore another Mary, who was called Salome, and from her was born James the Greater, and John, his brother. But Jerome contradicts this opinion in two ways. First, because Salome is not the name of a man, as also appears in the Greek, but is the name of a woman, who was the sister of the Blessed Virgin, and by Zebedee bore James the Greater and John, just as Mary of Cleophas by Alphaeus bore James the Less, Jude, and Simon. Now this James is called brother of the Lord specially among his other cousins, and this for two reasons: first, on account of a likeness of appearance, because he was like Christ in face; and on account of a likeness of life, because he imitated Christ in his ways. Or because Alphaeus his father was of the kinship of Joseph; and therefore, since the Jews were accustomed to trace the line of kinship from the males, and Christ was thought to be the son of Joseph, as is said in Luke 3:23, therefore he in particular was called brother of the Lord, and not the others, who were joined to him only through the mother. Here, however, "brother" is taken in the sense of kinship. For in Scripture "brothers" are sometimes said by nature. Matthew 1:2: "and Jacob begot Judah and his brothers." By kinship, as all blood relations are brothers. Genesis 13:8: "let there be no quarrel, I beg, between me and you, for we are brothers." By people, and thus all of one language are called brothers. Deuteronomy 17:15: "you may not set a man of another people as king, who is not your brother." By affection, and thus all friends, and those who have the same affection, are called brothers. 2 Corinthians 2:13: "because I did not find Titus my brother," etc. By religion, and thus all Christians who have one rule of life are called brothers. Matthew 23:8: "you are brothers," etc. Psalm 132:1: "behold how good and how pleasant it is for brothers to dwell together," etc. And commonly all men are called brothers, because they are governed and brought up by the one God. Malachi 2:10: "have we not all one father," etc. Next, when he says but the things that I write to you, etc., he confirms by an oath what he had said, as if to say: these things which I now write to you about myself, behold, they are in the open, so that it is sufficiently established that I do not lie. And this I say, before God, that is, with God as witness. Now the Apostle swears here not out of levity, but out of the necessity of those for whom it was necessary that they believe. For unless he did this, they would not believe him. 2 Corinthians 2:17: "before God, in Christ, we speak." Romans 1:9: "God is my witness," etc. What, then, does the Lord say: "let your speech be, yes, yes; no, no; what is more than this is from evil"? It must be said that it is from the evil of him who does not believe, or from the evil of the punishment by which someone is compelled to swear. Next, when he says then I came, etc., he shows how he was approved by the other churches of Judea. Here he does three things. First he shows where he stayed, namely, in Cilicia. Hence he says then I came into the regions of Syria and Cilicia, namely, of his homeland; whence also he had been carried off — for it is said at Acts 22:3: "now Paul was from Tarsus of Cilicia," etc. Second, how he was known by them, namely, not by face, but only by hearing and report. Hence he says for I was unknown by face to the churches of Judea that were in Christ, that is, in the faith of Christ. 2 Corinthians 6:8: "as unknown, and known." Whence it is clear that the churches of Judea did not teach me. For they had only heard, namely, of me by report, that he who persecuted, etc. Third, how he was approved by them, because they glorified God in me, that is, in my conversion they approved as great him who by his grace converted me. Isaiah 43:20: "the beast shall glorify me," etc.”

Post-Reformation

c. 1650 – 1900
1771
A.D.
John Gill Reformed
1697–1771
“Afterwards I came into the regions of Syria and Cilicia. For having disputed against the Grecians at Jerusalem, and being too hard for them, it so irritated them, that they were going to murder him; which being known to the brethren there, they got him out of the way, and had him down to Caesarea, and so to Tarsus, a city in Cilicia; where he was born; in which places and in the countries about he preached the Gospel of Christ; to Tarsus, Barnabas went for him seeking him, and finding him brought him to Antioch in Syria; and both in Syria and Cilicia he preached, no doubt with success, since we read of believing Gentiles and churches in those parts he afterwards visited; being sent along with others, with the letter and decrees of the synod at Jerusalem to them, and whom he confirmed; See Gill on Act 15:23, See Gill on Act 15:41, in the Greek text these countries are called "climates"; a climate in geography is said (y) to be a part of the surface of the earth, bounded by two circles parallel to the equator, and of such a breadth as that the longest day in the parallel nearer the pole, exceeds the longest day in that next the equator, by some certain space, viz. half an hour--. The beginning of the climate is the parallel circle wherein the day is the shortest, the end of the climate is that wherein the day is the longest;--each climate only differs from its contiguous ones, in that the longest day in summer is longer or shorter by half an hour in the one place than in the other:--vulgarly the term climate is bestowed on any country or region differing from another, either in respect of the seasons, the quality of the soil, or even the manners of the inhabitants, without any regard to the length of the longest day; in which sense it seems to be used here, as also in Rom 15:23. Of the country of Syria; see Gill on Mat 4:24. Cilicia is a country of Asia Minor, now called Caramania; it had its name of Cilicia, as Herodotus says (z), from Cilix, the son of Agenor, a Phoenician: though Bochart (a) derives it from Challekim or Challukim, which signifies stones, it being a stony country; and so Herodotus (b) calls it "mountainous" Cilicia; it is said to have Pamphilia on the west, the tops of Mount Taurus on the north, Mount Amanus on the east, and the Cilician sea on the south; Jerom says (c), Cilicia is a province of Asia, which the river Cydnus cuts in the middle, and Mount Amanus, of which Solomon makes mention, separates it from Syria-Coele. (y) Chambers's Cyclopaedia in the word "Climate". (z) L. 7. Polymnia, c. 91. Solinus, c. 51. (a) Canaan, p. 376. (b) L. 2. Euterpe, c. 34. (c) De locis Hebraicis, fol. 95. M.”
Source
1832
A.D.
Adam Clarke Methodist
1762–1832
“Afterwards I came into the regions of Syria, etc. - The course of the apostle's travels, after his conversion, was this: He went from Damascus to Jerusalem, and from Jerusalem into Syria and Cilicia. "At Damascus the disciples took him by night, and let him down by the wall in a basket; and when Saul was come to Jerusalem, he assayed to join himself to the disciples;" Act 9:25, Act 9:26. Afterwards, when the brethren knew the conspiracy formed against him at Jerusalem, they brought him down to Caesarea, and sent him forth to Tarsus, a city of Cilicia, Act 9:30. This account in the Acts agrees with that in this epistle.”
Source
1871
A.D.
1871
“I came into . . . Syria and Cilicia--"preaching the faith" (Gal 1:23), and so, no doubt, founding the churches in Syria and Cilicia, which he subsequently confirmed in the faith (Act 15:23, Act 15:41). He probably went first to CÃ&brvbrsarea, the main seaport, and thence by sea to Tarsus of Cilicia, his native place (Act 9:30), and thence to Syria; Cilicia having its geographical affinities with Syria, rather than with Asia Minor, as the Tarsus mountains separate it from the latter. His placing "Syria" in the order of words before "Cilicia," is due to Antioch being a more important city than Tarsus, as also to his longer stay in the former city. Also "Syria and Cilicia," from their close geographical connection, became a generic geographical phrase, the more important district being placed first [CONYBEARE and HOWSON]. This sea journey accounts for his being "unknown by face to the churches of Judea" (Gal 1:22). He passes by in silence his second visit, with alms, to Judea and Jerusalem (Act 11:30); doubtless because it was for a limited and special object, and would occupy but a few days (Act 12:25), as there raged at Jerusalem at the time a persecution in which James, the brother of John, was martyred, and Peter was m prison, and James seems to have been the only apostle present (Act 12:17); so it was needless to mention this visit, seeing that he could not at such a time have received the instructions which the Galatians alleged he had derived from the primary fountains of authority, the apostles.”
Source
Modern · 1953 →

The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.