七世紀後半，日本由於「自我中心意識」的發展，對外漸產生優越 感，並學習中國自成朝貢圈。此一「小帝國」的體制，由於大寶律令的制 定，更加確立。在「小帝國」當中，天皇或國家統治所及的範圍稱「化 內」，其外部教化所未及的區域稱「化外」。化外又分鄰國、諸蕃、夷狄 三類型。鄰國與日本是對等關係，諸蕃和夷狄則是向日本朝貢的臣屬關 係。諸蕃指朝鮮半島諸國、渤海，夷狄是列島內部未服教化，未形成國家 的諸種族，如蝦夷、隼人、南島人等。諸蕃和夷狄是確立「小帝國」構造 圈必備的條件，隋唐並不包括在內。 國書的交換和迎接外國使節的儀式，象徵此一國家的地位和權威。日 本與朝鮮半島國家、渤海間的外交，有如中國與周邊諸國，藉由外交文書 的交換和儀式，以建立其宗主國地位。但新羅和渤海兩國的使節，或用口 頭，或不攜帶國書，因而紛爭不斷。八世紀後半開始，兩國為能與日本順 利貿易，偶亦應日本要求，但實際上是以對等意識與日本往來。此外，至 九世紀，除奄美以南諸島未內屬，及九世紀末以後本州北端以北仍是蝦夷 地外，基本上都已成為「化內」，夷狄大致同化，「小帝國」的本質實際上已喪失。 七～九世紀，日本以其華夷意識，雖建立起「小帝國」的規模，但為 時短暫，當時隋、唐仍是國際秩序的中心。

Japan’s foreign policy, during the 7th through the 9th centuries, was to regard the Tang Dynasty as its neighboring country, while Korean Peninsular and Pohai, its subsidiary countries. The Emishi, the Hayato, and the natives of Southern islands, were being treated as barbarian tribes. Neighboring country was supposed to enjoy an equal relationship with Japan while a ruler-subjects relationship was established between subsidiary counties or barbarian tribes who were obliged to pay tributes to their Japanese ruler. This tributes offering circle with Japan as its center point is Japanese Views on the Compatriot-Barbarians Motivated by this concept, Japan had engaged in its foreign relationship with those countries and nationalities through exchanging of international credentials, reception protocols, and tributes offering and rewarding. However, it was the intense relationship with the Tang Dynasty, or the desire to establish international trade with Japan, not admiration for the “virtue” of Japanese emperor that had propelled those countries to offer their tributes. It was for this reason that, in the mid-8th century, diplomatic disputes often arose out of whether to present credentials or not. With the assimilation of the Emishi and the Hayato one after another, the “Tiny Empire” eventually existed without any substance and were in name only.