Answer:
Independence Post-WWII
Before we begin, take a few seconds to look at a current political map of the world. Pretty colorful, isn't it? Sure, there are larger swaths on the map, like Russia and Brazil, but Eastern Europe, Africa, and Southeast Asia all have several colors snaking around and crammed in between one another, don't they?
Well, a big reason for the numerous amount of countries in the world today is the process of decolonization that occurred after World War II (WWII) in Asia, Africa, and the Middle East. Indeed, as recently as 70 years ago, the political map of the world was far less colorful than it is today. Now, in 2014, there are over 200 nations on the planet!
Colonization
For nearly a half millennium, from the Age of Exploration through the 19th century, Western Europe had spent vast amounts of resources divvying up the territory, resources, and people of other continents. By 1900, nearly the entire continent of Africa, parts of South America, and most of Southeast Asia and the South Pacific were considered territories or colonies owned by countries like Great Britain, France, or Germany. After the dissolution of the Ottoman Empire after World War I (WWI), the Middle East was similarly split between Great Britain and France, who set up puppet states in the region to give some semblance of home rule.
Decolonization
Considering the expansive reach of the colonial system, from South America to Southeast Asia and everywhere in between, it's important to remember the diverse causes and experiences of decolonization. Indeed, where some countries were granted their independence by their colonial masters, others had to fight for it. Similarly, internal impetus for independence from the colonial powers varied greatly, and so did the colonizing countries' pressure from the international community.
Regardless, a few general trends should be noted. After WWII, national self-determination became an objective for some countries and international organizations like the United States and the United Nations. Proponents of national self-determination largely believed the inhabitants of a region should be able to decide what government is best for themselves. This anti-colonial international sentiment, coupled with a nation or people's demand for independence, often forced the hand of the colonial nations in this period, and helped make decolonization all the more likely. Now we'll cover the regions of the world colonized by the Western powers.
Middle East
The 1916 Sykes-Picot agreement between Great Britain and France secretly created the colonization of the Middle East. Both Great Britain and France already had troops in the region allied with local movements trying to weaken the Ottoman Empire. After the war, the French and British drew the lines of most modern states in the region, including Iraq, Lebanon, Syria, Transjordan, and Palestine.
The puppet states the Western governments set up were essentially under European control. This fact was made all the more apparent after WWII when Great Britain and the newly formed United Nations agreed to split Palestine in two and create the Jewish state of Israel. Much of the conflict and strife in the region today can be drawn back to these arbitrary borders drawn by the Western colonizers and the creation of Israel.
After WWII, the French and British came under serious pressure to eliminate their influence upon the Middle Eastern states, especially from the United States and the United Nations. Though the British did not relinquish their mandate of Palestine until after the creation of Israel, the French removed their mandate over Syria and Lebanon during WWII and recalled the last of its troops from the two new countries in 1946. Likewise, Transjordan became the Kingdom of Jordan in the same year when the British removed their own mandate.