"Their numbers have dwindled owing to smallpox and other causes to the extent that there is now barely one for every ten." Adriaen van der Donck, 1655.
Smallpox raged through the Native American communities who had no prior exposure, no immunity, no inherited partial resistance, and no clear way to treat the disease.
In 1658 an epidemic on Long Island resulted in the deaths of nearly two thirds of the Indian population, and this was not the first time that smallpox exposure had weakened these communities. So it is important to remember that Indigenous settlements had significant populations, with complex government structures, trading relationships, legal systems, and deeply founded cultures. The decimation of these populations by disease had a significant impact on the ability to 'pass on' culture, knowledge, and caused upheaval in governmental and family structures.
https://en.wikipedia.org/wiki/Shinnecock_Indian_Nation#:~:text=Native%2…;
https://en.wikipedia.org/wiki/Native_American_disease_and_epidemics