Afaik, by the middle of the
15th century, during its 'golden age', Brunei had started to expand.
The sultanate's control extended over the coastal regions of modern-day Sarawak and Sabah, the Sulu archipelago, and the islands off the northwest tip of Borneo. Keris were manufactured and kris imported from the Sulu regions.
Some useful references:
The Phillippine Islands: Explorations by Early Navigators, Descriptions of the Islands and their People, their History and Records of the Catholics Missions, as related in contemporaneous Books and Manuscripts. Vol. IV-1576-1582. Eds. Emma Helen Blair and James Alexander Robertson. Cleveland: The Arthur H. Clark Company, 1903.
Ongkili, James P. "Ancient Chinese Trading Links."
East Malaysia and Brunei. Ed. Wendy Hutton. Tuttle Publishing, 2001.
Saunders, Graham.
A History of Brunei. London and New York: RoutledgeCurzon, 2002.
Wright, Leigh. "Brunei: An Historical Relic." Journal of the Hong Kong Branch of the Royal Asiatic Society. Vol. 17 (1977).