In World War I, the Ottoman Empire, which controlled most of the Middle East, which is essentially Southwest Asia, was allied with Germany and Austria, and was thus on the losing side. The Ottoman Empire was dissolved and most of the Middle East was carved up into "mandates," pseudo-colonies governed by France or Britain with the intent of establishing them as self-supporting states. The boundaries of these mandates can still be seen in the present-day borders of Syria, Jordan, and Iraq. Since the mandate borders did not take into account cultural, ethnic, or historical boundaries, they are indirectly responsible for some of the sectarian violence within certain countries of the Middle East today. I believe modern Turkey and Saudi Arabia were also established soon after the war.
I hope this helps!