Quoting Commentary for I Kings 12:1

the daughters of one mother The two of them were from one nation, separated into two in the days of Rehoboam.

לא יסור שבט מיהודה, the position of royalty which all his 12 brothers bestowed on him, i.e. that they all prostrate themselves before him, will not be removed from him until Shiloh. Yehudah, i.e. King Rechavam of Yehudah son of Solomon who wanted to confirm his ascendancy to the throne in Shilo, which is very close to Shechem. (Kings I 12) [In the event, his stupidity in listening to inexperienced irresponsible counselors lost him most of his kingdom so that he ruled only over Yehudah and Binyamin. Ed.]

ולו יקהת עמים, “and to whom the gathered nations will belong.” The ten tribes will congregate at Shiloh to crown Jerovam as their head. This has all been spelled out in Kings I 12,1. The crowning took place at Sh’chem, but Shiloh and Sh’chem were practically next door (about 10 k.m.) to one another. Compare Joshua 24,1, and immediately after that Joshua 24,26 where Joshua is reported as recording all this “at the Temple of the Lord,” (which was at Shiloh) without any mention of Joshua having had to move to there to do this. This comment is mentioned here only as a reply to heretics who insist that Shiloh cannot be the name of a town, as a town is always feminine in Hebrew, so that the masculine יבא, “he will come,” would be inappropriate. Essentially, Yaakov describes the greatness of Yehudah as lasting from when David ascended the throne until his grandson Rechavam forfeited most of his kingdom. Seeing that Yaakov did not want to spell out the decline of Yehudah, he worded it in a manner that lets us draw these conclusions ourselves.

ויבא שכמה AND HE CAME TO SHECHEM — A spot foredestined to be the scene of misfortunes: there the sons of Jacob sinned (by selling Joseph), there Dinah was maltreated, there the kingdom of the House of David was divided, as it said (1 Kings 12:1) “And Rehoboam went to Shechem etc.” (Sanhedrin 102a).