"In 1993, the United Nation's Population Fund identified immigration as "the human crisis of the age." Its report pointed out that, historically, there were vast unpopulated spaces on Earth that were livable and where human beings could move in times of conflict, depletion of their local natural resources, climatological changes, or natural disasters. By the end of the 20th century, however, it is no longer possible to move en masse anywhere on the globe without confronting territory already occupied by others, Moreover, the report states that these would-be "recipient areas and countries are already under stress" themselves. Consequently, immigration is emerging ad the key issue confronting the governments of nation states everywhere."