The Otomo family (大友氏), which dominated a large part of northern Kyushu (九州) had a firm intention to trade in Southeast Asia. The Muromachi shogunate (室町幕府) ordered them to remit sulfur for export. Then Otomo Ujitoki managed two sulfur mines in the mountain district of Bungo (豊後). Otomo Chikayo expanded the mining business geographically, and built a big ship called the "Kasuga-maru (春日丸)". The Otomos dispatched trade ships to Korea, China, the Ryukyus (琉球), and several countries of Southeast Asia. In particular, Otomo Yoshishige and Ouchi Yoshinaga, who were brothers, dispatched a fleet to China for trade, but they were considered as smugglers by the government. They went to the coastal areas of the South China Sea, and traded with the merchants who passed through there.
In ancient Japan, manual labor was very important to administer the government ; and in provincial sub-divisions (gun 郡), "gun-zonin 郡雑任" were laborers who worked under the direction of "gun-ji 郡司 (administrators of gun)" ; but their specific activities have been unknown for lack of historical documents. The purpose of this paper is to clarify this aspect and also the origin of the institution. Investigation of recentry excavated "wooden-tablets 木簡" shows
Historians seem to regard the institution of the Caliphate as one of the most important problems in the Islamic political history. Even after the dissolution of the 'Abbasid Caliphate, that institution was still the main source of power and legitimacy, as seen in the Mamluk and Ottoman dynasties. It is generally understood that in the mid-ninth century when the amir al-umara' took over temporal power from the 'Abbasid Caliph, the Caliphate was reduced to a mere political symbol, granting legitimacy to the provincial regimes that were rising in various places at that time. A critical re-examination of the political relationships among the Buwayhid rulers and between the Caliph and the Buwayhid rulers, however, reveals that authorization by the 'Abbasid Caliph came not always into effect as the root of their legitimacy. In the earlier period, Buwayhid rulers were amirs appointed by the Caliph as his provincial officers. Acquiring the riyasa, which was the leadership of the Buwayhid family, became more important in claiming legitimacy after the struggle for power within that family. As a result, 'Adud al-Dawla, having won the riyasa of Buwayhid family, was no longer an amir appointed by the Caliph, but established himself as a "malik", meaning the holder of "mulk (sovereignty)", which did not originate from the 'Abbasid Caliphate. Judging from the above, the authority of the Caliphate as a political symbol was not always absolute, but rather was one of the several resources by which provincial regimes could legitimize their domination. So, when studying the development of political institutions after the emergence of the Saljuqid dynasty, must take the existence of malik and mulk into consideration.