Of the history of the indigenous population of California , Sherburne F. Cook (1896–1974) was the most painstakingly careful researcher. From decades of research he made estimates for the pre-contact population and the history of demographic decline during the Spanish and post-Spanish periods. According to Cook, the indigenous Californian population at first contact, in 1769, was about 310,000 and had dropped to 25,000 by 1910. The vast majority of the decline happened after the Spanish period, during the Mexican and US periods of Californian history (1821–1910), with the most dramatic collapse (200,000 to 25,000) occurring in the US period (1846–1910).   
Messengers were sent immediately to the Aztec empire 's capital: Tenochtitlan . As soon as Moctezuma got the news he believed it wasn't Quetzalcoatl, but perhaps other darker and less benevolent deities. He felt afraid and sent further messages telling the Spanish that it would be impossible to receive them in Tenochtitlan and urged them to leave as soon as possible, along with sending more presents of gold and other treasures. Once again, this only woke the greed of the conquistadors: Hernan Cortez realized the Aztec empire 's wealth was enormous...and also that the subjected peoples resented the Mexica. So instead, he went further inland instead of away.