Exposure to illnesses as a part of 'exploring' and or conquering territory is far from limited to North America.  Or perhaps you forgot about little epidemics like the black death (introduced into Europe from Asia).  You also seem to have forgotten about some of the mini epidemics that broke out in various ports throughout Europe after early expeditions to the Americas returned.  Finally you incorrectly put FAR too much weight on reports some morons tried to get natives sick by giving them 'infected' blankets.  1.  Simple greed is a much easier explanation and 2 the infections they were attempting to spread didn't spread that way and it was known that they didn't spread that way at the time. That kind of nonsense is like saying gay men were trying to spread HIV by holding hands.

As for the treaties, you must not follow history very closely.  The treaties with various tribes were all horribly flawed in multiple ways.
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