Congratulation to Prof. Nianshen Song on the publication of Making Borders in Modern East Asia: The Tumen River Demarcation, 1881–1919(Cambridge University Press, 2018). Based on Chinese, Korean and Japanase sources, the book focuses on a multilateral and multiethnic border between China and Korea during the fraught period that witnessed the Sino-Japanese War, the Russo-Japanese War, and the First World War.