Between 1663, when Zamboanga was abandoned, and 1718 when it was refortified, there was an interlude in the Moro Wars, which allowed the sultanates to become better organized and their Islamic institutions to be reinforced. Vigorous commercial relations with other principalities were initiated. It was around this time, too that the Sulu Sultanate acquired the North Borneo territory from the Sultan of Brunei as a grateful recompense for armed intervention in a dynastic quarrel. Sulu had reached the highest level of its territorial expansion. Actually, Sulu was simply filling up the power vacuum left in the island of Borneo as a result of Brunei's gradual political and commercial decline.