Sixteen Islands

A district of Katori City in the lowlands downstream of the Tone River in northern Chiba Prefecture. The Katori Sea once extended into the area, but during the Edo Period the Tone River was redirected toward Choshi, forming a low-lying marshland. In 1590 (Tensho 18), a group of samurai returned to farming and developed new fields on Kaminoshima Island. By 1640 (Kan'ei 17), Nishishiro, Yasujigawa, Nagashima, Rokkaku, Mishima, Oshima, Ougishima, Sakaishima, Bokui, Katouzu, Kessa, Nakajima, Matsuzaki, Nakazu, and Isoyama had been developed, and the area came to be known as the Jurokushima Islands. It is said that the Edo Shogunate had these new fields developed with the intention of defending the border with the Hitachi Satake domain, and the settlements are distributed like islands on the slight elevations along the Hitachi Tone River and Yoko Tone River, and many of the place names are "island" names. In 1957 (Showa 32), as part of the Tone River Specific Area Comprehensive Development Project, reclamation and land improvement of the area was carried out, and productivity improved as a producer of early-season rice.

[Yamamura Junji]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

千葉県北部、利根(とね)川下流低地にある香取市(かとりし)の一地区。かつて香取海(かとりうみ)が深く湾入していたが、江戸時代に利根川の河道が銚子(ちょうし)方向へと変えられ、低湿地が形成された。1590年（天正18）に帰農した武士団が上之島(かみのしま)の新田開発を行い、以後1640年（寛永17）までに西代(にししろ)、八筋(やすじ)川、長島、六角、三島、大島、扇(おうぎ)島、境島、卜杭(ぼっくい)、加藤洲(かとうず)、結佐(けっさ)、中島、松崎、中洲(なかず)、磯山(いそやま)を開拓して十六島とよばれるようになった。江戸幕府が常陸(ひたち)佐竹藩領との境界防御を意図して新田を開かせたといわれ、集落は常陸利根川と横利根川沿岸の微高地上に島状に分布し、島の地名が多い。1957年（昭和32）に利根川特定地域総合開発事業の一環として、一帯の干拓、土地改良が進められ、早場米の産地として生産性を向上させた。

［山村順次］

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