During the reigns of Sujin and his successor, Suinin, the agriculture and communication of the country are recorded to have been greatly encouraged, troubles near the court exterminated, and also the area of the empire largely extended. The extension of the imperial domain, however, brought it in sharp conflict with the still unsubdued tribes of the north and the south. From the reign of Keikō, Suinin's successor, we hear of the story of the conflict. The Kumaso of Tsukushi, Kiushū, rose in arms. How seriously this was regarded is seen from the fact that the emperor in person conducted a campaign for several years in Kiushū. No sooner was peace restored than the southern tribes again rebelled. This time the brave Prince Yamato-dake, who was sent to Tsukushi to subdue the insurgents, had to resort to strategy instead of war. Having disguised himself as a girl, he obtained entry into the house of the Kumaso chief, where he killed the chief and his warriors while they were lying drunk. He also overthrew many other rebellious princes and returned to Yamato in triumph. In the meantime the emperor, after his return from Kiushū, had heard from a special commissioner whom he had sent that in the northeast of the empire there was a strange region named Hidakami, where the people of both sexes wore their hair tied up, tattooed their bodies, and performed deeds of valor. They were known as the Emishi, and their land, being extensive and fertile, the commissioner represented, ought to be added to the imperial domain. These Emishi rose in rebellion shortly after the return of Prince Yamato-dake from the conquest of the Kumaso. Thereupon the prince boldly offered to undertake the conquest of the new insurgents. After subduing local uprisings on his way, he proceeded by sea to the region of the northern rebellion. As his boats drew near the shore he displayed a large mirror at the prow of his vessel, and when the rebel chieftains and their followers sighted the ships, they were terrified by such evidences of pomp and power, and throwing away their bows and arrows, made submission. The prince accepted their homage, and enlisting their aid, conquered other rebels who still resisted the progress of the imperial forces. It seems probable that on that occasion Prince Yamato-dake advanced as far as the present province of Iwaki. On his return journey, which was again beset with local difficulties, he was seized with a severe illness, which soon proved fatal. The emperor bitterly lamented the death of his beloved son, and the story of the gallant prince is still dear to the heart of every child of Japan. [Illustration: JAPAN AS KNOWN TO THE EMPERORS BEFORE THE FIFTH CENTURY]