Japanese Pirates in the Beginning of the Heian Period [1-1]

First of all, as far as pirates are supposed to be those sailing on the seas, attacking other boats and stealing things from them, there must have been other boats to be attacked and those boats must have been carrying things. Then, what boats were carrying what things in the Seto Inland Sea in the 9th century? Things carried officially are comparatively easy to grasp. As early as in 756, the central government ordered the regional governments around the Seto Inland Sea to send their tax rice to the capital by rowboat, and added, if the tax rice on a boat was lost, 30% of it should be taxed again to the original taxpayers and 20% to the forwarders according to the order issued in May, 735. The Japanese ancient centralized bureaucratic government had been established in 645. They imposed 3 types of taxes: So, tax rice; Yo, labor duties; Cho, tax cloth. All the taxes were supposed to be carried to Kyoto by Yo itself. That is, all the taxes were carried on taxpayers’ shoulders. As boat-building skills improved, and navigating skills matured, water transportation might have increased so much as the government could not ignore within a century. 111 years after the establishment of the tax system, Yo also had become rice, and all the tax rice including Yo came to be carried by rowboat around the Seto Inland Sea.