"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.
Colonists arriving in 1633 at Plymouth, Massachusetts, unwittingly spread the virus to local Native American communities. By 1634 it reached the Mowhawk nation, and by 1636 the Lake Ontario area. Between 1613 and 1690 the Iroquois tribes living in Quebec suffered twenty-four epidemics, almost all of them caused by smallpox. Some historians estimate that almost 90% of the Native American population died of diseases brought by Europeans during the 17th century.
https://en.wikipedia.org/wiki/Shinnecock_Indian_Nation#:~:text=Native%2…;
https://en.wikipedia.org/wiki/Native_American_disease_and_epidemics