The same thing happened to the native North Americans too. When the Pilgrims showed up in Massachusetts in 1620, the whole region between there and maine had been reduced in population by 90+% due to a plague inadvertently brought by traders
The thing was that _any_ outside contact was going to be doom for North America. A lack of resistance and no sanitation equaled a tinder box just waiting for the right plague.
The thing was that _any_ outside contact was going to be doom for North America. A lack of resistance and no sanitation equaled a tinder box just waiting for the right plague.