Whatever be the intrinsic merit of the reform itself, there is no doubt that the reform came from necessity. It was absolutely necessary that Japan, in order to make solid progress, should be centralised politically. The model which the reformers selected was the legislation of a strongly centralised monarchy. In this respect at least it admirably fitted the necessity of Japan at that time. In the year 659, fifteen years after the promulgation of the reform, an organised expedition consisting of a large number of squadrons, was despatched along the coast of the Sea of Japan as far north as the island now called by the name of Hokkaido. In the next year another expedition was sent across the sea to the continental coast, perhaps to the region at the mouth of the Amur. Though the frontier line on the main island was not pushed forward against the Ainu so rapidly as the progress along the western coast, owing to the obstinate resistance of the tribe on the eastern coast, yet the victory was wholly on the side of the Japanese. The removal of the imperial residence by the Emperor Tenchi in the year 667 to the side of lake Biwa, in the province of Ohmi, marks an epoch in the progress of the exploration north-easternward. For the new site, a little distant from the modern town of Ohtsu, is more conveniently situated than the former residences, not only in guarding and pushing the north-eastern frontier, but in keeping connection with the navigation on the Sea of Japan. The inland lake of Biwa, though not large in area, is one which must be counted as something in a country as small as Japan. Until quite recent times, communication between Kyoto, the former capital, and Hokkaido and the northern provinces of Hon-to was maintained, not along the eastern or Pacific shore, but via the Lake and the Sea of Japan. Even the eastern coast of the province of Mutsu seems to have had no direct communication by sea with the centre of the Empire. In order to reach there from the capital, men in old times were obliged to take generally a long roundabout way along the western coast, pass the Strait of Tsugaru, and then turn southward along the Pacific coast. This important highway of the sea route of old Japan was connected with Kyoto by the navigation across lake Biwa. The change of the imperial residence to the neighborhood of Ohtsu, which is the key of the lake navigation routes, had no doubt a great historic significance.