The empire that fell after World War I due to widespread nationalist movements was the Ottoman Empire. As the war concluded, various ethnic groups within the empire, such as Arabs, Kurds, and Armenians, sought independence and self-determination. The empire's defeat in the war, coupled with the rise of nationalist sentiments, led to its disintegration and the establishment of new nation-states in the region. The Treaty of Sèvres in 1920 and subsequent agreements further dismantled Ottoman territorial claims, paving the way for the Republic of Turkey, established by Mustafa Kemal Atatürk. This transformation marked a significant realignment of power in the Middle East.