_Prehistoric Period._--Thus, if the most rigid estimate be accepted, the space of 1160 years, from 660 B.C. to A.D. 500, may be called the prehistoric period. During that long interval the annals include 24 sovereigns, the first 17 of whom lived for over a hundred years on the average. It seems reasonable to conclude that the so-called assignment of the sovereignty of Japan to Sosanoo's descendants and the establishment of their kingdom in Izumo represent an invasion of Mongolian immigrants coming from the direction of the Korean peninsula--indeed one of the _Nihongi's_ versions of the event actually indicates Korea as the point of departure--and that the subsequent descent of Ninigi on Mount Takachiho in Hiuga indicates the advent of a body of Malayan settlers from the south sea. Jimmu, according to the _Chronicles_, set out from Hiuga in 667 B.C. and was not crowned at his new palace in Yamato until 660. This campaign of seven years is described in some detail, but no satisfactory information is given as to the nature of the craft in which the invader and his troops voyaged, or as to the number of men under his command. The weapons said to have been carried were bows, spears and swords. A supernatural element is imported into the narrative in the form of the three-legged crow of the sun, which Amaterasu sends down to act as guide and messenger for her descendants. Jimmu died at his palace of Kashiwa-bara in 585 B.C., his age being 127 according to the _Chronicles_, and 137 according to the _Records_. He was buried in a kind of tomb called _misasagi_, which seems to have been in use in Japan for some centuries before the Christian era--"a highly specialized form of tumulus, consisting of two mounds, one having a circular, the other a triangular base, which merged into each other, the whole being surrounded by a moat, or sometimes by two concentric moats with a narrow strip of land between. In some, perhaps in most, cases the misasagi contains a large vault of great unhewn stones without mortar. The walls of this vault converge gradually towards the top, which is roofed in by enormous slabs of stone weighing many tons each. The entrance is by means of a gallery roofed with similar stones." Several of these ancient sepulchral mounds have been examined during recent years, and their contents have furnished information of much antiquarian interest, though there is a complete absence of inscriptions. The reigns of the eight sovereigns who succeeded Jimmu were absolutely uneventful. Nothing is set down except the genealogy of each ruler, the place of his residence and his burial, his age and the date of his death. It was then the custom--and it remained so until the 8th century of the Christian era--to change the capital on the accession of each emperor; a habit which effectually prevented the growth of any great metropolis. The reign of the 10th emperor, Sujin, lasted from 98 to 30 B.C. During his era the land was