Japanese Pirates in the Beginning of the Heian Period [2-2]

Japanese pirates made their major debut on May the 20th, 862. One document says: “These days, pirates frequently form groups, kill travelers, and rob varieties of goods no matter they belong to the government or civils. According to the Bizen government, ‘80 koku’ of tax rice was robbed by pirates at last. They were sending the tax rice to Kyoto. They loaded the rice on a boat, and forwarded the boat with pullers tugging it with ropes. They, however, encountered pirates, were robbed of everything, and got 11 of their men killed. The governors of Harima, Bizen, Bicchu, Bingo, Aki, Suo, Nagato, Kii, Awaji, Awa, Sanuki, Iyo, and Tosa were promptly ordered to send their men to chase the pirates.” It is not clear how much rice “80 koku” represented at the time in Japan. In today’s sense, 1 koku = 10 to = 100 sho = 1000 go, and 1 go of rice weighs about 150 grams, but metrology differs from a time to another, and from a country to another, say in China. They might have been using a different metrology. I also wonder if they could load 12 tons of rice on a boat in Japan in the 9th century. However, the robbery of that much tax rice must have been such a shocking news that the central government issued an order for chasing and arresting pirates for the first time in the Japanese history. The document also suggests that the number of pirates who had become organized was increasing, and their piracy was becoming more common and persistent.