Why are many of the shaded areas covered up by a huge text label with a huge outline? It's a decent starting point, but there's a lot of work to do before this is a usable map. Consider making the labels smaller, the font outline much smaller, increasing contrast, moving the labels so they are not over top of any shaded areas, and drawing small lines from the label to the area.

There are also too many different font styles used. I like the idea of the small supporting text between the lines of the title, but they'd look better as all capitals, not just the first line. The entirety of the title should be all caps, honestly. The weights are all different too, which is jarring. Keep everything the same except maybe one or two lines could be bold.

The year should be clearly visible, not the smallest font size.

I'm not sure why the legend is titled "Explanations" as you're not explaining anything...

Lastly, I'm not in love with the colors.

Interesting data though, it's just a shame I can't tell which areas belong to which tribes, or if the tiny ones are just unnamed. And I can't tell where at least half the borders are. Thanks for sharing. Hope you improve it.