מלכים א, פרק ט״ו, פסוק ט״ז

The biblical narrative briefly pauses its ongoing storyline to establish the broader political and security landscape between the divided kingdoms [ביאור שטיינזלץ]. The ongoing struggle was not a personal feud between two rival kings. Instead, it represented a direct continuation of the deep-seated tension and constant friction between the Kingdom of Judah and the Kingdom of Israel. This dynamic persisted under the new northern dynasty founded by Baasha, who took power after Nadab, the son of Jeroboam [מצודת דוד, ביאור שטיינזלץ].

A broader view of the historical record presents a slight timeline challenge, as the book of Chronicles notes that a state of peace existed until the fifteenth year of Asa's reign. To resolve this, the statement that the two kings fought throughout their entire lives is understood to mean that the fighting lasted continuously from the moment their active conflict first began [מצודת דוד]. Leading up to that breaking point, the relationship was marked by constant minor skirmishes and border friction, while the major, official war only erupted into full-scale combat during Asa's fifteenth year on the throne [מלבי״ם].