About 12,000 Iroquoians around 1745
There had been nearly 100,000 Iroquoians in 1500. By 1745, there were barely 12,000.
This number included the (now) Six Nations Iroquois who still occupied their ancestral territory (south of Lake Ontario, in what is now part of New York State in the U.S.), the Huron-Petun who had been dispersed and were now living in the Lake Huron and Lake Michigan region, and the Catholic Iroquois and Huron who were living in Indigenous villages in the St. Lawrence Valley. These last two groups had about 4,500 people.
What might explain such a huge decline in the Iroquoian population between 1500 and 1745?
All the Indigenous nations had been hit hard by diseases introduced to North America by the Europeans, like smallpox, typhus, measles and influenza. Indigenous people did not have the necessary antibodies to protect themselves, and were therefore more vulnerable. Everywhere the French went, outbreaks of disease followed. The French did not intentionally cause these outbreaks, but the result was truly catastrophic for the Native population.
Wars for fur and prisoners
Indigenous nations had been fighting each other to become the main suppliers of furs and to have the most important role in trading with the Europeans. As a result, wars had increased since the arrival of Europeans. So had the number of deaths caused by war. Wars were also used to capture prisoners. Among the Iroquois, these prisoners were adopted to replace the many people who had died from the epidemics.
[Notes: The Tuscarora were accepted in 1722 as the Sixth Nation of the Iroquois Confederacy, or Haudenosaunee.]