In the fifth year of King Rehoboam, because they had been unfaithful to the LORD, Shishak king of Egypt came up against Jerusalem
Israel was very much disgraced and weakened by being divided into two kingdoms; yet the kingdom of Judah, having both the temple and the royal city, both the house of David and the house of Aaron, might have done very well if they had continued in the way of their duty; but here we have all out of order there. I.
Commenting on 2 Chronicles 12:1-12
And it came to pass in the fifth year of Rehoboam,.... In the fourth year, the apostasy of him and his people began; and, in the year following, what is next related happened, as a punishment of it: Shishak king of Egypt came up against Jerusalem; of whom see Kg1 11:40, because they transgressed against the Lord; transgressed the law of the Lord by falling...
Shishak king of Egypt came up against Jerusalem--He was the first king of the twenty-second or Bubastic Dynasty. What was the immediate cause of this invasion? Whether it was in resentment for some provocation from the king of Judah, or in pursuance of ambitious views of conquest, is not said.