The Gemara tells us that Sefer Melachim should be viewed as one large sefer. This sefer was written by the prophet Yirmiya and is full of ups and downs in its recording of an extremely turbulent and eventful approximately 400 year period of Jewish history. Sefer Melachim begins with the reign of Shlomo Hamelech, which was the most tranquil period in our history. The Bnei Yisrael were united, the nations were in awe of Bnei Yisrael, there was no war, and the Beis Hamikdash was built. However, Sefer Melachim then details the splitting of the kingdom into the kingdoms of Yisrael and Yehuda, and also records our incremental exile and the destruction of the Beis Hamikdash. It was during the span of Sefer Melachim that the prophets Yeshaya, Yirmiya, Hoshea, and Yechezkel prophesied.
The Sefer is called Melachim as it details 41 out of 44 kings of Klal Yisrael (excluding David who died at the beginning of the Sefer) who lead the entire people or either of the two kingdoms. A king of Bnei Yisrael is more than a mere social leader who ensures law and order; he leads the people in the service of Hashem, and is called the ‘Mashiach Hashem,’ (this is the term David used in expressing his unwillingness to kill Shaul Hamelech even when the latter was pursuing him). The king has special laws which pertain both to him and to how the people are to treat him. This is why, the bracha on seeing a king of Klal Yisrael describes the ‘honor’ bestowed on kings as coming from ‘Hashem’s honor’
In the Introduction to the “Nechmad La’Mareh” edition of Sefer Melachim, there is an interesting distinction drawn between the kings of Yehuda and those of Yisrael. The kings of Yisrael are connected with Yosef (for their first king was Yeravam, who was a descendant of Yosef), while the kings of Yehuda are from the tribe of Yehuda. And since a central trait of Yosef was emotion (regesh; in Bereishis, the Torah gives us three instances of Yosef crying), the kings of Yisrael were also governed by emotion. This trait is also true of Yosef’s sole maternal brother, Binyamin (perhaps this emotion originated from Rachel), which was the root of Shaul’s mistake in his misplaced mercy on the people of Amalek in Shmuel Alef. In contrast, the kings of Yehuda inherited Yehuda’s trait of putting mind (sechel) over emotion, in the same way that Yehuda rose above the emotions displayed by his brothers, and managed to save Yosef from death in the pit by suggesting that he be sold instead. Thus, Shlomo Hamelech, a descendant of Yehuda, was the epitome of this trait of sechel. It is perhaps for this reason that, in general, the kings of Yehuda were more loyal to Hashem than the kings of Yisrael; for they had greater wisdom, and could recognize Hashem’s ultimate control without being blindly led by emotions. We learn that emotions are important, but they have to be tied down and governed by sechel (intelect). Though there is an essential difference and split between the kings of Yehuda and the kings of Yisrael (different laws apply to each of them), in the future there will only be one king and one kingdom, as the prophet Yechezkel (37:19) tells us.
Each generation varied greatly from the generation it preceded and likewise to the generation that preceded it, as we see that Chizkiyah, one of the most righteous kings, bore Menashe, one of the most wicked kings. The ten lost tribes of Yisrael are described, as is the exile in which we remain until today. Sefer Melachim also describes the splendor of the Beis Hamikdash and eventually, its destruction. Sefer Melachim describes the highs and the lows of the Jewish people throughout this period; this is what it means to be part of the Jewish people to connect to both the peaks and the troughs of Jewish history.