This chapter explores the under-examined relationship between war, and commerce, and diplomacy in the Sino-Korean borderland of the late Ming period. It discusses the manner in which the war mobilization for the Ming campaign in Korea in the final decade of the sixteenth century drew upon the existing networks of merchants in the Sino-Korean borderland. Thus reads one of the opening passages of the Korean textbook of the Chinese language titled Laoqida or Nogoltae, which was first compiled in the late Koryo period and remained in use for official language training throughout the subsequent Choson period. The revised late fifteenth-century edition of this textbook narrates a Korean merchant’s journey to the Ming capital of Beijing, accompanied by two of his relatives and a neighbor. The Laoqida presents a neatly constructed worldview and draws a clear boundary between China and Korea along the Yalu River.