The Spaniards knew how to deal with thieving negritos.
The first European exploration of the area was that led by Ferdinand Magellan in 1521, who landed on nearby Guam and claimed the islands for Spain. The explorers were met offshore by the native Chamorros, who delivered refreshments to them and then helped themselves to a small boat belonging to Magellan's fleet. This led to a cultural clash because in the old Chamorro culture there was little if any private property and to take something that one needed, such as a boat for fishing, was not considered theft.
Due to that cultural misunderstanding, around half a dozen locals were killed and a village of 40 homes were burned by the Spanish before the boat was retrieved. The archipelago thus acquired the ignominious name Islas de los Ladrones ("Islands of the Thieves").