What evidence is offered by the author to show that millions of native Americans died from disease?

The author presents historical records indicating that European colonization brought diseases such as smallpox, measles, and influenza to which Native Americans had no immunity. These records include accounts from colonists and explorers who documented the rapid decline of Indigenous populations following contact. Additionally, demographic studies reveal significant population decreases in Native American communities coinciding with the introduction of these diseases, highlighting the devastating impact on their populations.