The exact borders are not fully clear, as the regions are not official political or administrative units.
For example, although the Dzūkian dialect is called South Aukštaitian, it does not mean that Dzūkija is part of Aukštaitija.
However, some work was done recently to delineate their boundaries more clearly, as there is a project to change the system of counties in Lithuania into ethnographic regions, which would be called lands (žemės).
Another supporting argument is that in other countries historical territories are being revived, while in Lithuania artificially made counties exist.
However, if the reform were to be implemented, most likely there would be just four lands, not five, because most of Lithuania minor is located within the modern borders of Russia (in the Kaliningrad Oblast) and many Lithuanians were expelled from there.