In Parashat VaYechi, the Torah records that part of Ya’akov Avinu’s blessing to Yehudah was that “Lo Yasur Sheivet MiYehudah”, “the royal scepter will not depart from Yehudah” (BeReishit 49:10). This meant that the royal lineage would remain in the tribe of Yehudah forever. However, there were multiple kings over the Bnei Yisrael who were not from the tribe of Yehudah, namely Shaul, Yerovam, and the members of the Chashmona’i dynasty. This presents an important challenge. How were these kings appointed, if they weren’t from the right tribe? Yerovam and Shaul were both appointed by Hashem through Nevi’im-- Achiyah HaShiloni and Shmuel, respectively. They too were also promised to have a dynastic reign. How can one reconcile the existence of these dynasties with Ya’akov Avinu’s Berachah to Yehudah?
Rambam (Hilchot Melachim 1:9) answers the question in relation to Malchut Yerovam by postulating that the offer to Yerovam of a “Bayit Ne’eman”, “a lasting dynasty” (I Melachim 11:38) was not everlasting. Ra’avad writes that the offer to Yerovam had potential to last forever, but that both Malchut Yisrael and Yehudah could coexist as continual dynasties; albeit, Yerovam’s dynasty would assume a secondary status. Ramban (BeReishit 49:10 s.v “Lo Yasur”) explains that Yerovam’s rule was specifically not meant to be an eternal dynasty, and that the Bnei Yisrael sinned when they continually appointed king after king that were not part of the Davidic dynasty after Yerovam’s death.
Ramban (ibid.) also explains how Shaul was able to be appointed as king. He explains that at that time, Hashem found the concept of a monarchy inappropriate, since the Bnei Yisrael had improper intentions in their request for a king, as recorded in I Shmuel 8, “Lo Otecha Ma’asu Ki Oti Ma’asu Mimloch Aleihem”, “For it is not you that they have rejected; it is Me they have rejected as their king.” Hashem therefore made Shaul a temporary king-- it was a “Malchut Sha’ah.” However, Ramban also records that had Shaul not sinned, he would have continued to rule over at least the tribe of Binyamin.
Ramban continues and explains how the Chashmonaim became kings after the Chanukah story. They were a holy and pious family, and they played an important role in the perpetuation of Judaism; but, nonetheless, as they were Kohanim and not from the tribe of Yehudah, they were punished greatly for attempting to ascend to the throne. Another reason they were punished was that they sinned by trying to take power not granted to them by their priesthood. Ran (Drishut HaRan HaDarush HaShevi’i) argues with the Ramban regarding the status of the Chasmona’i kings, based on the fact that their rule did not constitute a true Malchut. A king must rule independently; any king who is subject to another political power is not considered to be a true Melech. The Chasmona’im were subject to the Greco-Persian authority, and therefore did not count as kings that were not from the tribe of Yehudah. The Ran argues that there was no requirement to have a king from Yehudah in such circumstances, as a valid Malchut did not exist at that time.
Rashi (BeReishit 49:10 s.v “Lo Yasur”) disagrees, and holds that even in times where the Bnei Yisrael are ruled by someone else, as they were during the Babylonian exile, a king from the tribe of Yehudah is still required. Lastly, the Seforno (ibid.) writes that when there is a Jewish monarchy, once there is a king from the tribe of Yehudah, that king will have an eternal dynasty.
Be’Ezrat Hashem, may we merit to see the renewal of the Davidic dynasty speedily in our days.