[6] Pengiran Muda Saiful Rijal was the eldest son of Sultan Abdul Kahar,[7] therefore making him the successor to the throne after his father's abdication in 1530.
[8] A significant statement from the Boxer Codex, likely written by a Tagalog merchant who lived in Brunei, describes Saiful Rijal as a cheerful and stout man, noting that he was fifty-eight years old in 1589.
Therefore, if these dates are accurate and considering the four sultans from Sharif Ali to Abdul Kahar, it indicates that there must have been a succession of brothers at some point in the royal lineage.
Manila charged Brunei of conducting Muslim missionary activities in the Philippines because of the Spaniards' zealous proselytising efforts to convert the entire archipelago to Christianity.
In a letter dated 13 April 1578, to Brunei's Sultan Saiful Rijal, the Spanish Governor of the Philippines, Francisco de Sande, made the following accusation and gave the following order.