At the beginning of the Spanish Era, colonisers heard of the rich gold mines in the mountains and attempted to colonize the highlands, but failed. In 1572, Spanish "conquistador" Juan de Salcedo led a small expedition into the southern part of Benguet, but the natives forced it to retreat. The first major expedition into the mountains occurred in 1620, when Spanish explorers went into the La Trinidad Valley, followed by a second expedition in 1623, and a third in 1624. This was the last attempt to occupy the Baguio gold mines by the Spanish until the Galvey expeditions (1829-1839).