Do we know what illness(es) were involved? What was the population loss in numbers, if we can estimate? What approximate time period was the die-off of local humanity in?
hi! the "plague" was several previously-unknown infectious diseases - most notoriously smallpox, but also others - carried by the Europeans and introduced into the native population. Knowing this usually raises a few follow-on questions: (1) Did a similar epidemic also occur when the Norse arrived in Greenland/Newfoundland ca 1000AD? (no) (2) Did Europeans also contract diseases from the native peoples? (yes, but to a lesser extent) and (3) Did the Europeans realize what was happening? (not initially, but later yes)
These topics are discussed in these sections of the FAQ (link on sidebar):
Some other common follow-on questions include (1) did the same thing happen in in other areas colonized by Europeans (Africa, Australia, etc)? (2) Were native peoples of Latin America impacted to the same degree, that is, why is there a higher % of people of native extraction? If you run a few searches in this sub for "native disease" or "smallpox", you'll find many related posts.
As far as before Europeans arrived to the continent? Possibly smaller breakouts but nothing widespread. However, there are many records of sweeping and decimating epidemics that would spread in various ways to more isolated populations such as in the West Coast of North America prior to European human arrivals but after they had been introduced to the continent and began introducing biota into the newly discovered Americas. European diseases (that the indigenous Americans had never previously been exposed to) were able to spread via animal as well as other Americans. Quarantine strategies were often utilized in which the ailing and dying would be abandoned and the healthy would flee and introduce it into a new population. These diseases were extremely devastating to the populations as well as equally devastating to New Zealand and Australia in a similar fashion.
Source: Ecological Imperialism: The Biological Expansion of Europe, 900-1900, Studies in Environment and History; Alfred W. Crosby
Could you perhaps point me to a source where you've read this? In my experience, I've never heard of such a hypothesis.