Why did European diseases cause a major decline in the Indigenous population of British Columbia?

The major decline of the Indigenous population in British Columbia following European contact was primarily due to the introduction of contagious diseases for which the native peoples had no prior exposure or immunity.12

These diseases, which included smallpox, measles, and venereal infections, were brought to the region by colonists and traders. Because these illnesses were new to the Indigenous populations, they caused extremely high mortality rates. It is estimated that between 1780 and 1900, the Indigenous population in the region declined by as much as 80 percent.32

The impact of these epidemics was profound, leading to significant social disruption, the loss of ritual and practical knowledge, and the forced reorganization of societies due to the rapid death of community members. While the introduction of these diseases was the most disruptive factor, the overall demographic collapse was also compounded by the broader effects of colonialism, including displacement, poverty, and the loss of traditional lands.243