Well, if they were diverse beforehand, then they'd be diverse afterward (just fewer in number). As long as you make your method of genocide wide-reaching but not 100% effective, then you'll still have a lot of different types of lizardfolk. Eg, something like a nuke will destroy 100% of the lizardfolk of a specific tribe, so that would be bad for your purposes, because the only way for a tribe to survive would be to not be targetted at all. On the other hand, something like a gas attack would leave the strongest and luckiest alive, so even if every tribe was hit with it, there would still be a lot of lizardfolk types remaining.
Really from Jupiter, but not an alien.Not every people “come together” after a tragedy and here you’re dealing with another species. Maybe living in large groups just isn’t in Lizard Folk nature or maybe, despite the human’s war against them, the Lizard Folk have had conflict between each other’s tribes for so long that even a common enemy can’t unite them.
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Thanks for the idea, but I don't think my world has any fantastical nukes at this point.
Good point, Thanks.
Yes, this is because genocide will disperse people. As a general rule, they aren't ALL going to stick around and wait for their death to come. If there's even a few that have the foresight to run the crap away, they will do so.
This results in several small groups running in different directions, which means that they arise differently from each other. If you thinking "well the Jews all stayed pretty much the same even after genocide"—the Jewish people are atypical of what normally happens, because they have a very, very strongly bound culture—not to mention there's STILL plenty of Jewish offshoots, they just tend not to identify as 'Jewish' any longer.

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I'm currently working on a fantasy world, where an evil human empire just had an attempted genocide on Lizard folks/Lizard-men believe them to be demons. The problem is I already have them down as being very diverse and vastly different in make up from one tribe to another. What are some ways I can justify this diversity after their race was nearly wiped out?
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