Born in Congosto, in El Bierzo Region (León), he was the nephew of Lope García de Castro, viceroy of Peru.

Sarmiento de Gamboa developed an interest in Inca stories of gold and riches being collected from lands further to the west.

"Restless and disruptive" elements in the Spanish Americas were encouraged to join such journeys of exploration to remove them from colonial society.

However, the Spanish expedition's need for fresh food and water quickly led to tension and conflict as the islanders were unable to provide supplies after some time.

However, the attempts to barter for food led to the same cycle of friendly welcome, misunderstandings, sullen retreats, occasional reconciliations, robberies and violent retaliation.

[3]: 129  Finally, at a council meeting of captains, pilots, soldiers and sailors on 7 August 1568, the decision was made to return to Peru.

Mendaña had wanted to sail further south, while Sarmiento de Gamboa and several soldiers unsuccessfully urged the establishment of a colony.

These discoveries led to successive expeditions in search for Terra Australis, both by Mendaña himself and by Pedro Fernandes de Queirós.

[7] A much larger and costlier expedition had been planned by the early 1590s, after Mendaña had spent years courting favour in Madrid and Lima.

[8] On 21 July 1595 the ships reached the Marquesas Islands, (named for the wife of the then viceroy of Peru, García Hurtado de Mendoza, 5th Marquis of Cañete) to be met by four hundred people in canoes.

[2]: 85 Pedro Fernandes de Queirós is credited with bringing the San Gerónimo safely into the Philippines without the aid of charts, arriving in Manila Bay on 11 February 1596.

[12] The frigate (carrying Mendaña's body) disappeared during the voyage, while the galiot San Felipe arrived in the southern end of Mindanao several days later.

[2]: 88–90 Back in Peru in June 1597, Queirós began his campaign to return to the Solomon Islands, leading the next Spanish venture in 1605.

This expedition was also unsuccessful, but it led to the discovery of the Pitcairn Islands and Vanuatu which were explored, and briefly settled in the case of Espiritu Santo.