This is an interesting document. In 1877 Baron de Overbeck applied and got the concession for Sabah. He and another Englishman Edward Dent later on got a company called the North Borneo Company and ran Sabah from then on until it was taken over by the British. Sabah came into being with this document where Baron de Overbeck was made the Emperor of Sabah (Maharaja Sabah) and King of Gaya and Sandakan. Baron de Overbeck was a clever man and he knew the history of Sabah. Sabah was at that time technically Brunei but Brunei was supposedly to have given up Sabah to Sultan Sulu during the Brunei Civil War. So, to be on the safe side, Baron de Overbeck when to Sultan Sulu and in January 1878, Sultan Sulu also made him Dato Bendahara and Raja Sandakan. Sabah at that point in time was more or less under the influence of Sultan Sulu.
What is intriguing about this document and another document (that of Sultan Sulu) was this these were included in Sultan Hassanal Bolkiah's commemorative book on His Majesty's ascension to the throne. Why these? Were these the only historical documents Brunei could find then? I am not pretty sure why but I sure am curious.