At the end of WW1 Ottoman Empire collapsed, Ottoman Empire covered Southwest Asia. The European powers that included Britain and France took over this region. Territories controlled by the Allied power after WW1, were called mandates; these were created by Britain and France. Ethnic and religious differences caused mandates to claim independence from foreign rule and become a nation-states.

One of the most significant examples of this was the creation of the modern state of Turkey following the collapse of the Ottoman Empire. Mustafa Kemal Atatürk led a successful nationalist movement and established the Republic of Turkey in 1923.

Similarly, the mandates of Iraq and Syria eventually gained independence and became independent nation-states in the 1930s. The borders of these new states were often drawn without regard to the ethnic and religious makeup of the region, leading to tensions and conflicts that continue to this day.

Overall, the aftermath of WW1 and the collapse of the Ottoman Empire had a profound impact on the political landscape of Southwest Asia, shaping the modern borders and identities of the nations in the region.