After a long age of empires, modern nation-states established a new culture of territorial borders, which became rigidly precise and widely reported in international treaties and documents. Globalization brought a revolution in its wake, leaving borders in many cases porous and virtually insignificant from a social, economic, and even legal point of view. But history dances inexorably on, and this weakness has now been targeted and challenged by the political proponents of doctrines of national sovereignty. The pressures of what can be defined as a post-globalization period have seen the nature of borders change yet again, wavering between rigidity in some cases and extreme porosity in others.