World Systems Analysis
"World Systems Analysis" is a school of thought advocated by many historians and other scholars which looks at the progression of history from what Kenneth Waltz would call "the third level of analysis". Advocates of this school contend that from the beginning of recorded time through the mid seventeenth there existed what scholars call the "system of world empires". This system was characterized by four attributes: Firstly, it was possible for several empires to exist at the same time. Second, empires spread through military conquest or the threat of military conquest. Third, each empire was self-sufficient in the fact that it independently provided for the greater majority of its economic needs. Finally, each empire was roughly equivalent to any nearly empire that existed at the same time, militarily, technologically, economically, etc. 
Scholars who support this theory contend that starting with the Peace of Westphalia in 1648, the empire system began to collapse through a series of shocks and changes. Firstly, after the aforementioned Peace of Westphalia, the Hapsburg empire began to collapse and a new world system started to emerge in Europe. Even scholars who do not support world systems theory generally cite the Peace of Westphalia as the starting point for the modern system of nation-states. Also during this time the world economy exhibited what scholars call the "great inflation", which affected virtually every government on the Eurasian continent. Advocates of world systems analysis contend that this was one of the major causes that led to the decline and collapse of empires across Eurasia. They contend that to maintain their powerful armies and centralized bureaucracies, these empires faced serious problems when confronted with this inflation and continually found themselves short of money. 
Finally, the rise of the European powers, and their accompanying economic policies, in the 18th and 19th centuries confirmed the "modern world system's" rise, which the system that current International Political Economy scholars focus on today.
 - Gelvin, James L. The Modern Middle East: A History Oxford University Press. New York 2008. pg 39.
 - Gelvin, James L. The Modern Middle East: A History Oxford University Press. New York 2008. pg 35.