Are we saying that Europeans never discover the Americas or that there just isn't any transfer of disease? The first is sort of implausible. As ship building

Are we saying that Europeans never discover the Americas or that there just isn't any transfer of disease? The first is sort of implausible. As ship building techniques improve in Europe the ease of finding the Americas would tend to increase. Without Columbus the Portuguese were going to run into Brasil while trying to sail around Africa pretty soon. Without the Portuguese then northern European fishing fleets would pursue Cod into Nova Scotia at some point. Technological progress tends to build on itself so bootstrapping from what were similar to bronze age city states without the bronze to ocean crossing flotillas would probably take closer to 2,000 than 200 years. If we just remove disease then colonialism proceeds differently and more slowly but still proceeds. Agricultural settlers have a tendency to push back hunter gatherers everywhere for population density reasons and I think that would be true of Europeans wanting to start farms in the colder parts of North and South America just as it was in Russia's expansion east across the continent or anywhere else. Hungry people living in Malthusian conditions are almost invariably assholes to people who are different from them. Without the introduction of malaria in particular there's a much denser settlement in many parts of the Americas. Influenza killed off a large proportion of the native inhabitants across the Americas but often they recovered their numbers if Europeans didn't move in. The introduction of Malaria essentially made large scale agricultural civilization impossible in large swaths of the US South, Mexico, the Caribbean and the Amazon basin except for people who had developed a partial immunity by living in areas suffering from that disease for many generations. People talk about the people of Jamestown starving because they were lazy or looking for gold but really it was mostly because they were suffering from "Tertian Fever" and unable to work. The native Virginians were suffering in the same way but sadly didn't leave written records. Malaria was eventually eliminated in the US in the early 20th century. I can't find a good historical online map of malaria but it more or less corresponds to the current range of the Ae. aegypti mosquito. https://elifesciences.org/articles/08347/figures https://elifesciences.org/articles/08347/figures I expect that there would still be colonialism but that it would look a lot more like colonialism in South Asia, Indonesia, and the Philippines - happening later and incompletely.