At the very mouth of the Pasig River was the island called Maynila. As a town, it was just becoming well-known. In fact, it may have been founded only a couple of generations earlier. In the 1520s it was known in the Visayas but by the 1560s the Visayas had already heard of the Kingdom of Maynila.
On its throne sat a young king: Rajah Soliman, who was Muslim and Bornean. His wife was Bornean too and so were his palace guards. Soliman was a warrior. The petty kingdoms along the river and on the lake lived in mortal terror of him. They cried that he was forever swooping down on them, to raid and plunder.
According to Nick Joaquin, what Soliman may have been doing was organizing the barangay colonies into a nation. With his raids on the petty kingdoms of the river and lake, Soliman may have thought to reduce them into a single commonwealth: a unit, a union, a unity welded under his government.
If unification was indeed his dream, he would see it fulfilled but not under his government.
Information source: Manila, My Manila by Nick Joaquin