Osorkon II died around 837 BC and is buried in Tomb NRT I at Tanis. He is now believed to have enjoyed a reign well in excess of 30 Years, rather than just 25 Years. The celebrations of his first Sed Jubilee was traditionally thought to have occurred in his 22nd Year but the Heb Sed date in his Great Temple of Bubastis is damaged and can be also be read as Year 30, as Edward Wente noted. The fact that this king's own grandson, Takelot F, served him as High Priest of Amun at Thebes–as the inscribed Walls of Temple J prove – supports the hypothesis of a longer reign for Osorkon II. Recently, it has been demonstrated that Nile Quay Text No.14 (dated to Year 29 of an Usimare Setepenamun) belongs to Osorkon II on palaeographical grounds. This finding suggests that Osorkon II likely did celebrate his first Heb Sed in his 30th Year as was traditionally the case with other Libyan era Pharaohs such as Shoshenq III and Shoshenq V. In addition, a Year 22 stela from his reign preserves no mention of any Heb Sed celebrations in this year as would be expected, (see Von Beckerath). While Osorkon II's precise reign length is unknown, some Egyptologists such as Von Beckerath – in his 1997 book Chronology of the Egyptian Pharaohs –. and Aidan Dodson have suggested a range of between 38 to 39 years. However, these much higher figures are not verified by the current monumental evidence. Gerard Broekman gives Osorkon II a slightly shorter reign of 34 Years.
Osorkon II was most likely succeeded by King Usimare Setepenamun Shoshenq III who ruled Egypt's 22nd Dynasty for 39 Years according to contemporary historical records. Two Apis Bulls were buried in Year 4 and Year 28 of his reign and he celebrated his Heb Sed Jubilee in his Regnal Year 30. Little is known of the precise basis for his successful claim to the throne since he was not a son of Osorkon II and Shoshenq's parentage and family ties are unknown.
From Shoshenq III's Regnal Year 8, his reign was marked by the loss of Egypt's political unity, with the appearance of Pedubast I at Thebes. Henceforth, the kings of the 22nd Dynasty only controlled Lower Egypt. The Theban High Priest Osorkon B (the future Osorkon III) did date his activities at Thebes and (Upper Egypt) to Shoshenq III's reign but this was solely for administrative reasons since Osorkon did not declare himself king after the death of his father, Takelot II. On the basis of Osorkon B's well known Chronicle document, most Egyptologists today accept that Year 25 of Takelot II is equivalent to Year 22 of Shoshenq III.
Shoshenq III had at least 4 sons–Bakennefi A, Pashedbast B, Pimay who was known as the 'Great Chief of the Ma, son of the Lord of the Two Lands, Shoshenq', and Takeloth C–but they all appear to have predeceased their father through his nearly 4 decade long rule. Shoshenq's third son, Pimay ('The Lion' in Egyptian), was once thought to be identical with king Pami ('The Cat'), but it is now believed that they are two different individuals, due to the separate orthography and meaning of their names.