In 1576, Governor-General Francisco de Sande sent a request to meet with Sultan Saiful Rijal, expressing a desire for good relations with Brunei.

De Sande assumed the title of Capitán-General and assembled a fleet carrying 200 Spaniards, 200 Mexicans, 1,500 native Filipinos (Luzones), and 300 Borneans.

[9][10] In addition to native Malay warriors, Bruneian forces were supported by the Ottomans who had been sent in several expeditions to the nearby Sultanate of Aceh and were composed of Turks, Egyptians, Swahilis, Somalis, Sindhis, Gujaratis, and Malabars.

[11] These expeditionary forces spread to nearby Sultanates and taught local mujahideen new fighting tactics and techniques to forge cannons.

It gradually set aside its policies of territorial expansion and developed into a city-state, surviving to the modern day as the oldest continuously Islamic political entity.