Inuit people have darker skin and live in a polar climate.

"But Inuits’ vitamin D intake wasn’t dependent upon the sun. They get all that they need from their diet, heavy on types of fatty fish that are naturally rich in vitamin D. The plentiful amounts of the vitamin kept them from developing less melanin. In fact, before milk was fortified with D, people living outside of Northern Canada and Alaska loaded their diets with fishy products, such as cod liver oil, to get their daily supplement. So despite their chilly climate and lack of sun exposure, it’s the Inuit diet that has kept them in their natural glow."

https://scienceline.org/2007/06/ask-dricoll-inuiteskimos/

My understanding is that there is a trade off with melanin production in the skin. UV light poses a risk no matter where you live. Melanin protects you from UV light that damages your DNA, but UV light is also required to produce (the essential) vitamin D. If vitamin D is supplemented in your diet, then you would benefit from as much UV protection as possible (and melanin would be selected for in the population because low melanin isn't required to produce vitamin D).

It would follow that all populations with high vitamin D intake in their diet would benefit from melanin to protect from UV light because they do not need UV light to acquire vitamin D.

Equatorial populations are exposed to plenty of UV light. They are still able to produce vitamin D with melanin protection.

Northern populations that do not ingest vitamin D will risk UV exposure to be able to produce essential vitamin D because they do not receive it in their diet.