It is interesting to note that under the simple rule of the Kamakura government the commerce and trade of this period made a tolerable progress, in spite of frequent interruptions of the peace. At Kamakura, where merchants from various parts of the empire assembled and made it the commercial center of the country, there existed seven kinds of markets in which articles were sold at small stores specially designed and constructed. The custom of peddling merchandise also existed. For business transacted at a distance, bills of exchange had already come into vogue. While Sanetomo administered the shōgunate, an official limit was fixed for the number of merchants conducting business in Kamakura. This was the origin of hereditary privileges of trade. The prices for the various staples of commerce were determined, according to the custom of previous times. Thus in 1193 an imperial notification ordered that rice should be sold at one thousand cash (one _kwammon_), or the tenth of a _ryō_, that is to say nominally ten _sen_ according to present denominations, but of course representing a much larger sum at that time. Again, in 1253, firewood, charcoal, and other necessaries having risen in price, Hōjō Tokiyori proclaimed the rate at which each must be sold. Gold was at that time constantly mined in Mutsu, but did not serve for coinage purposes, the common media of exchange being Chinese copper and the iron cash of the Sung dynasty and similar Japanese coins of earlier days. Grass-cloth was also sometimes used as a medium of exchange, and prices were quoted in terms of it. Trade with China, under the Sung dynasty, and with Korea--or Koma, as it was then called--was carried on largely at Hakata in Chikuzen and Bonotsu in Satsuma, both in Kiushū. Import duties upon foreign goods were levied at the various ports of entry. The principal imports from China were raw silk, indigo, Chinese ink, porcelain vessels, mats, and so forth, while the staple exports from Japan were rice, other cereals, and timber. In 1254 Hōjō Tokiyori limited the number of ships engaged in the China trade to five, and ordered all except the licensed vessels to be destroyed. But the trade continued as brisk as ever. Subsequently, however, during the interval that separated the decline of the Sung dynasty from the establishment of the Yuan, intercourse between Japan and the neighboring empire underwent some diminution, and was suspended altogether for a time after the Mongol invasion of Japan. FOOTNOTES: [1] Table showing lineage and chronology of sovereigns.