In 1540 Gonzalo Pizarro, the Conquistador's brother, set out on an expedition to the fabled Cinnamon Country, thought to lie somewhere to the east of Quito.

The party that set off from Cuzco comprised 180 soldiers, 3000 local Indians, a contingent of African slaves, 100 horses and 600 war dogs. After passing through Huanuco, the expedition entered San Francisco de Quito, where Gonzalo Pizarro recruited Francisco de Orellana as his lieutenant.

The party marched on to Quitzos, the outermost of the Inca provinces. Having penetrated deep into the jungle, Pizarro had his men build a brig, which he christened the " San Pedro " and placed under the command of Francisco de Orellana . The ship proceeded down the Santa Ana river as other troops advanced along the bank. While difficulties encountered on the way forced Pizarro to camp by the Santa Ana (previously known as the Coca river), Orellana descended the Napo river and on February 12, 1542 came upon a vast expanse of water, which turned out to be the confluence of the Amazon river and the Napo 's two branches. The discovery of the mighty Amazon - the world's most copious river - was thus the crowning achievement of a memorable expedition that had set out from Cuzco , capital of ancient Peru .