Born in Secadura de Trasmiera, Spain,[1]: 398  Alvarado served under Hernán Cortés in Mexico before joining Francisco Pizarro's campaign in Peru.

While some contemporaries accused him of greed and brutality, Alvarado remained loyal supporter to Spanish crown throughout the Peruvian civil wars.

The chronicler Pedro Cieza de León mentions the first founding of Chachapoyas: On the fifth of September in the year of the Lord one thousand five hundred and thirty-eight Ihsu Christo, with sixty Spaniards under the control of captain Alonso de Alvarado arrived in [...] "Xalca" and made the first foundation of Chachapoyas.Captain Luis Valera, father of the Cachapoya Jesuit Blas Valera, was also present at the founding.

[3]: 260, 264 Following Francisco Pizarro's orders, Alvarado sought an ideal location for a city halfway between Lima and Cusco in 1539.

In 1541, Diego de Almagro II ("El Mozo") assassinated Francisco Pizarro, seeking revenge for his father's death.

The following year, Governor Cristóbal Vaca de Castro, allied with Alvarado, defeated El Mozo at the Battle of Chupas.

Though obsessed with finding this mythical treasure, their expeditions faced unforeseen hardships – famine, disease, hostile indigenous people, and the treacherous rainforest itself.

[citation needed] The El Dorado envisioned by the conquistadors was a city with streets and temples paved with gold, embellished with massive golden structures and plazas.

While the legend itself proved to be a myth, it nonetheless opened doors for the initial colonization and evangelization of vast, remote regions of South America.