The fortress of Nutari had been for a long time the outpost of the Japanese against the Ainu on the side of the Sea of Japan. With this fortress as a pivot the boundary line gradually turned toward the north, pushed forward by the arms of the Japanese. The movement must have been made at a very unequal pace in different ages, and where the progress was very slow or stopped short and could not go on for a long time, there we may draw another boundary line, thus marking several successive stages. Politically to efface the significance of these lines was thought to be necessary for the unification of the Empire by the Emperors and their ministers in successive ages, and in that respect more than enough has been achieved by them. Apart from political considerations, however, those lines, which mark the boundaries in successive phases, are almost perceptible to this day. And none of those lines is so full of meaning as the one which I have emphasised above. At first sight it would seem strange that while the fortress of Nutari remained stationary as an outpost for a very long time, there cannot be found any corresponding spot on the Pacific side east of the line. But the difficulty may be cleared away easily, if one thinks of the fact that the line was moved on more swiftly to the right than to the left where the fort Nutari was situated. In the first half of the third century after Christ the Japanese were still fighting on the line against the Ainu. And the time when the Chinese officials came over to this country falls in the same period. In the description given in the _San-kuo-chih_ the names of about thirty provinces under the suzerainty of the court of Yamato are mentioned, to identify all of which with modern names is a very difficult and practically a hopeless task. But this much is certain, that none of them could have denoted a province east of the line. Moreover, we can tell from a passage in the same work that the war with the Ainu at that time had been a very serious one for our ancestors, for it is stated that the course of the war was reported to the Chinese official stationed in the peninsular province by the Japanese ambassador despatched there.