There is evidence that as early as the last years of the fifteenth century, Islam was already gaining headway in many places in the Philippines. It was carried directly from or via Sulu or Mindanao by preachers, traders or voyagers from Borneo who settled among the inhabitants of the islands. In the words of one popular writer:
The Muslims were the ruling class in Luzon, the rich traders, cultural leaders and missionaries, the ones with the knowhow and the right connections, the literacy and what's more, the right religion.
What is Metropolitan Manila today was formerly the bastion of Islam. Manila was ruled by Rajah Sulaiman Mahmud, jointly or assisted by Rajah Matanda, his uncle and Tondo under the rule of Rajah Lakandula. Manila was not only the commercial center but a powerful fort (cotta) was built near the mouth of the Pasig River in defense of the realm.
It was to the islamized natives of Manila that the word Moro was first applied by the Spaniards in 1570 to denote those who professed Islam. Indio first denoted the pagan natives, but was later to include even the christianized. It was only in later years, more specifically in 1578 and after, that the name Moro was generally applied to the Muslims of Mindanao and Sulu.