It is almost impossible to ascertain from reliable sources how far back we can trace our connection with the peninsula. According to a chronicle of Shiragi, a state which once existed in the southeast of the peninsula, one of the Japanese invasions of that state is dated as early as 49 B.C. Since the value of the chronicle as historical material is very dubious, it is dangerous to put much faith in this statement at present. We may, however, venture to assume that in the first half of the third century A.D. the intercourse between Japan and Korea became suddenly very intimate. Japan invaded the peninsula more frequently than before, and our emissaries were despatched to the Chinese province established to the north of it. Nay, not only that, some of them penetrated into the interior of China proper, as far as the capital of Wei, and on the way back seem to have been escorted by a Chinese official stationed in the peninsular province. Memoirs by those Chinese who had thus opportunities of peeping into a corner of our country, were incorporated by Chen-Shou, a Chinese historian at the end of the third century, in his general description of Japan, a chapter in the _San-kuo-chih_, which has remained to this day one of the most valuable sources concerning the early history of our country. This intercourse between the peninsula and Japan, sometimes friendly and sometimes hostile, happened to be accentuated by the expedition of the Empress Jingu to Shiragi in the middle of the fourth century. Soon after this expedition, Chinese civilisation, which had achieved a considerable progress during the long Han dynasty, began to flow into Japan, and effected a remarkable change in both the social and the political life of our country. For just at this time the two northern states of the peninsula, Korea or Kokhuri and Kutara, advanced rapidly in their civilisation, so that a school to teach Chinese literature was founded in the former, while in the latter a post was instituted in the royal service for a man of letters. And Shiragi, another state in the south-eastern part of the peninsula, ceased to be a barrier to communication between those two peninsular states and Japan, as it had been before the expedition of the Empress.