The name Peru is derived from the word “Biru.” When the Spanish conquistadors arrived in Central America between 1521 to 1522, they found that the ruler of what is now present day Panama was a man named Biru. They called the region to the south of Panama as Biru.
The Spanish conquerors knew very little of the language or of the land that lay to the south of Panama and so they referred to Peru as Biru. It was Francisco Pizarro who explored the region that lay to the south of Panama.
Some historical accounts state that Biru was the name of an unknown local Inca who assisted the Spanish explorers in exploring the new world. In 1529, the monarch of Spain granted legal status to the name and thus Biru or Peru came into existence.