The correct answer is "false."
It is false that prior to nationalism natural boundaries were what divided states.
The concept of nativism was developed in the 1600s by Hugo Grotius in the times of the Eight Years War when the Netherlands fought against Spain for Independence.
Nativism was the nationalistic movement that tried to defend the ideas of people in a certain region or territory, favoring their own culture, traditions, and belief systems over the other territories. In some cases, natural barriers helped to limit or separate territories in Europe but that was not the general case.
Nativism defended the concept of a region's sovereignty to protect the territory against the influence of other regions' ideas or forms of government.