"Мої племінниці живуть на сході."

Translation: My nieces live in the East.

[Konrad-Michal]

Would that mean without context: in the East of Ukraine?

[deactivated user]

I don’t think it’s possible to say this without any context, because you’re bound to be in some place when speaking. So, it would refer to the east of the place you’re currently in. If this conversation happens in Ukraine, then it’s the East of Ukraine. If the conversation happens in Portugal, then it’s the East of Portugal.