In the year 794, the Emperor Kwammu transferred his capital to the province of Yamashiro, and gave it the felicitous appellation of Hei-an, which means peace and tranquility. The place, however, has been commonly designated by the name of Kyoto, which means literally the capital, and continued henceforth to be the centre of Japan for more than one thousand years. There might have been several motives which caused the capital to be removed from Nara. The valley, in which the old capital was situated, might have been too narrow to allow free expansion, or it might have been found inconveniently situated as regards communications. Party strife among the nobles might have been another reason. At any rate the choice of the new site cannot be regarded as a mistake. Kyoto is better connected with Naniwa, Osaka of the present day, than Nara was at that time. From Kyoto one was able to reach the port within a few hours, by going down the river Yodo by boat. There is no natural hindrance on the way like the mountain chain which divides the two provinces of Yamato and Settsu. At the same time, Kyoto is quite near to Ohtsu, the gate toward the eastern provinces, and those selfsame provinces were the regions which had for long been engrossing the attention of far-sighted contemporary statesmen. The energetic Emperor Kwammu undertook the conquest of the Ainu with a renewed vigour. That part of the Ainu country which faced the Sea of Japan was already made a province before the accession of that sovereign. In the Emperor's reign the success of the Japanese arms was carried far into the Ainu land by the victorious general Sakanouye-no-Tamuramaro. The boundary of the province of Mutsu, the region facing the Pacific, was pushed northward into the middle of the present province of Rikuchu. Enterprising Japanese settled in those lands or travelled to and fro in quest of trade. The Ainu, however, was not completely subjugated, nor was he easily driven away out of the main island. Beyond Shirakawa, the place which had for a long time been considered the northernmost limit of civilised Japan, numerous hordes of half-domesticated Ainu continued to reside as before. As the result of the constant contact with the Japanese, they were slowly influenced by the civilisation which the latter had already acquired. They could consolidate their forces under the leadership of some valiant chiefs, and frequently dared to rise against oppressive governors sent from Kyoto. In short, they proved to be intractable as ever, so that more than three centuries were still necessary to put their land in the same status as the ordinary Japanese province. The interminable wars and skirmishes waged thenceforth between the two races were one of the principal causes of the financial embarrassment of the government at Kyoto, and finally undermined its power.