This article considers the meaning of Goguryeo-Sui War and Goguryeo-Tang War in East Asian history in terms of both state system and international relations. These wars were a continuation of great war mobilizing large-scale armies. Mobilization of large-scale armies was based on the reformation of the weapon and military systems, which was paired up with the aligning of a centralized state system. It also promoted the strengthening of centralization and made power of influence. In the 7th century, Baekje, Silla, and Japan engaged directly or indirectly in the war, and strengthened the centralized state system. This interlocking was closely related to the development of transportation. War was accompanied by the development of transportation, because it was possible by moving militaries and military supplies. Overland, waterborne and marine traffic route connecting Northeast Asia, inland Asia, and Central Plains of China developed evenly. The alignment of a centralized state system in several East Asian countries was achieved through cultural exchanges, and the development of transportation vitalized this. The development of transportation accompanied by war led East Asia to one world of history. Goguryeo-Sui War and Goguryeo-Tang War in the 7th century called for change based on the change of ancient society in East Asia.