Complex sentence: Political, legal, religious, cultural, social, and economic policy changes were designed to convert the new Republic of Turkey into a secular, modern nation-state and implemented under the leadership of Mustafa Kemal Atatürk.
Split into simpler sentences: Political, legal, religious, cultural, social, and economic policy changes were designed to convert the new Republic of Turkey into a secular, modern nation-state. These changes were implemented under the leadership of Mustafa Kemal Atatürk.