So you are denying that the events happened as recorded in the Bible?
You can't just address a tiny little factoid like this and make any sense out of it. You have to discover the purpose of Scripture itself, and allow it to say what it says, rather than attempting to impose our own ideas upon it. Joshua - 2 Chronicles covers a
heritage of Israel, passed down as oral history, not written down until perhaps as late as the Babylonian exile many hundreds of years later.
You and I cannot know if Amalekites ever existed or not, but we sure can know what they
represent in the story. What difference does it make to our lives today if they existed or not? Its not the purpose of Scripture. Stories like this are INTENTIONALLY shocking, and horrible. So if you guys want to hang out and go "how shocking and horrible," that's a valid use of passages like this. If you want to do anything with it more than that, like maybe understand it or assign meaning to it, you'll have to use it in the way intended, which means to listen to those who have spent years and decades living with the harsh reality of what it says, and pondering it.
And of all the things you could pick from the Bible, this is just not a likely starting point. I have no idea what frame of reference anyone here has but I do know for a fact that everyone's is different, and if any glimmer of understanding were to pass on to one individual, it wouldn't likely make sense to anyone else in this diverse bunch, starting here.
So far what we have established in this thread about this all came about with Loudmouth:
God isn't some ignore reality and just do whatever dude, He's just and constrained to the reality He created, which is complex;
Nobody was killed due to their race so genocide isn't even an applicable
concept; what's happening in all these gory stories is judgment according to works;
Even though genocide is an anachronism most of these slaughtered groups were warned ahead of time, giving the pacifists among them time to flee. This leaves only the warlike left in harm's way, which is a specific part of God's Judgment, which while controversial can be seen as an extension of the Judgment of the flood. Its key to target those that are warlike, and understanding these details definitely helps tie the whole of Scripture together.
If you were asking a complex question about a complex circumstance and expecting a simple answer - that was foolish wasn't it?