דברי הימים ב, פרק ט׳, פסוק ל׳

The era of King Solomon's leadership was defined by national unity and unprecedented political change. Over the course of four decades, a kingdom that previously relied on basic agriculture and a citizen militia shifted into a powerful state. It developed extensive foreign relations, a highly skilled military, and widespread maritime trade. This broad transformation established significant infrastructure that supported the nation for generations to come [ביאור שטיינזלץ].

The primary approach among commentators highlights a fundamental difference between the forty-year rule of Solomon and the forty-year rule of his father, David. Although both kings led the nation for the same amount of time, David did not govern the entire population from the very beginning. During his early years, David ruled solely over the tribe of Judah from the city of Hebron. Only later did he relocate to Jerusalem to lead the rest of the tribes. Solomon, on the other hand, maintained a completely united kingdom, leading the entire nation as one cohesive entity throughout his entire forty years on the throne.