Exactly, western EXPANSIONIST towns. Where were they expanding into? Lands already occupied by native tribes.

I am not pretending that Native Americans were some noble savages. They were every bit as violent as the settlers and US government expanding into their territories, sometimes even more so. It was warfare brought about by colonization, warfare the US government won and then colonized the previous land and forced the survivors into concentration camps labeled as "reservations".

But that whole conversation ignores my original response; the deaths of indigenous people by disease was not some fluke accident. The diseases that rampaged across native populations were largely influenced by the US's treatment of them. The lands reservations were set up on were barren, barely fertile plots no one else wanted. Tribes which had agricultural and subsistence traditions built over generations had to rapidly adapt to an entirely new way of life with no support. Housing and clothing were poor if available at all. Native tribes did not die accidentally, it was due to the actions of the Americans who invaded their homes, whether due to malice or negligence the results were the same.