Hi, I'm Spanish and sadly my historic education was really eurocentric, the whole conquista was treated as a sidenote where Colon found América and then it kinda happened.
But as far as I know the conquista was done with little investment in numbers.
I'm inclined to think that even with the conquistadores playing the natives against each other and the superior weaponry the conquest would have been almost impossible with a more solid ruler and the whole army, specially the Incas since that mountain territory should really hard to navigate for an invasor.
So my questions are:
Are there similar occurrences with conquest in Asia/Africa (established kingdoms/empires) without such a big disease impact? What happened, the same or they were able to hold better.
Were the weaponry so superior or the real strength was the surprise and alliances with other local tribes.
Any insight on that era would be great, thankyou for your time.
Yes. Because the Spanish conquered South America, at least they conquered the Incas, without help from smallpox.
There's actually very little evidence for smallpox in the Andes before 1558. The cause of death for Huayna Capac is conflicted in the sources, but re-examining of the sources and finds in archeology suggest it was likely not smallpox.
A few researchers has pointed out that the descriptions and known circumstances make bartonellosis, a less-studied new-world disease, much more likely.
Which does not mean the Spanish weren't helped by disease. They were, just a new-world one, not an old-world one.
If you are thinking of the Aztecs, however, that is another issue. Source evidence for smallpox epidemic striking Mexico and the Caribbean in 1520 are much more solid, and it definitely greatly helped in the conquest of Tenochtitlan (though whether that help is "decisive", as in could the conquest have happened without it, is another question altogether considering the epidemic also struck Cortes' allies, and of course its impossible to measure this kind of "contribution" or know what would've happened without the disease). However one needs to remember most of the dying took place after conquest (two cocoliztli epidemics in 1545 and 1576), when, like in most of the new world, population collapse was due to harsh conditions imposed by the colonizers greatly exacerbating epidemics and preventing their recovery, by /u/Kochevnik81 and /u/Anthropology_nerd.