How can statistics describe Italy or Germany before unification?

How can historical statistics cover Italy or Germany before those countries were unified?

The likely basis is the geographical area before unification. The series are recalled as reaching back to about the 1700s, although their exact coverage is not checked here.

A country's later name can identify a geographical area when discussing an earlier period. That is the suggested explanation for historical statistics labeled Italy or Germany before unification. The starting dates are recalled from memory, leaving the precise coverage of either volume uncertain.