Azumie - Abokukou

...means "black river" in Vietnamese. It originates in the northern gorge of the Ailao and Murai mountain ranges in central Yunnan, China, and was first called the Amojiang River and then the Li Xian River. It becomes the Son Da River when it enters Vietnam. At Lai Chau, it joins the Na River (known as the Teng Tiao River in China), which also flows south, and like the Song Khoi River, it flows from northwest to southeast, forming a gorge along the syncline axis of the mountain folds in this region.

*Some of the terminology explanations that mention "Azumi-e" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…ベトナム語で〈黒色の川〉の意。中国の雲南省中部，哀牢山系と無量山系の北部峡谷に発源，はじめは阿墨江，次いで李仙江とよばれ，ベトナム領内に入ってソンダー川となる。ライチャウで同じく南流してきたナー川(中国領内では藤条江)を合わせ，ソンコイ川と同じくこの地方の山地の褶曲の向斜軸に沿い，北西から南東に峡谷をつくって流れる。…

※「阿墨江」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報