We can not wonder, therefore, that modern historiographers have devoted much labour to tracing the route followed by Yamato-dake's troops and rationalizing the figurative or miraculous features of the narratives told in the Kojiki and the Nihongi. It is enough to know, however, that he overran the whole region stretching from the provinces along the Eastern Sea as far as Iwaki; crossed westward through Iwashiro to Echigo on the west coast, and turning southward, made his way through Shinano and Mino to Owari, whence, suffering from a wound caused by a poisoned arrow, he struggled on to Ise and died there. This campaign seems to have occupied ten years, and Yamato-dake was only thirty at the time of his death. He had marched against the Kumaso in the south at the age of sixteen. The Chronicles relate that when crossing the Usui Pass and looking down on the sea where his loved consort had cast herself into the waves to quell their fury, the great warrior sighed thrice and exclaimed, "My wife, my wife, my wife!" (Ago, tsuma haya), whereafter the provinces east of the mountain were designated Azuma.
It was imagined until quite recent times that the pass referred to was the well-known Usui Toge on the Nakasendo road; but Dr. Kume has shown that such a supposition is inconsistent with any rational itinerary of Yamato-dake's march, and that the sea in question cannot be seen from that defile. The pass mentioned in the Chronicles is another of the same name not far from the Hakone region, and the term "Azuma" "had always been used to designate the Eastern Provinces." Throughout the Records and the Chronicles frequent instances occur of attempts to derive place-names from appropriate legends, but probably in many cases the legend was suggested by the name. In connexion with Yamato-dake's career, a circumstance is recorded which indirectly points to the absence of history at that period. In order to immortalize the memory of the hero, hereditary corporations (be) called after him were created. These Take-be gave their names to the districts where they lived, in Ise, Izumo, Mimasaka, and Bizen.
Another custom inaugurated by this sovereign was to require that the rulers of provinces should send to the Yamato Court female hostages. The first example of this practice took place on the occasion of an Imperial visit to the regions overrun by Yamato-dake's forces. Each of twelve kuni-yatsuko (provincial rulers) was required to send one damsel for the purpose of serving in the culinary department of the palace. They were called makura-ko (pillow-child) and they seem to have been ultimately drafted into the ranks of the uneme (ladies-in-waiting). Japanese historians hold that the makura-ko were daughters of the local magnates by whom they were sent, though the fact of that relationship is not clearly stated in either the Records or the Chronicles.