Where does “南北アメリカ” come from?

南北アメリカ (Japanese) comes from Japanese アメリカ, from English America, from Latin America, from Italian Amerigo, from Proto-Germanic *Amalarīks, from Proto-Germanic Haimarīks, from Proto-Germanic rīks, from Proto-Celtic rīxs — to straighten, to right oneself; right; just.

Ancestry of “南北アメリカ”, step by step

南北アメリカ traces back through 3 separate lines of ancestry.

via Japanese アメリカ

StepLanguageWordMeaning
1JapaneseアメリカAmerica, United States
2EnglishAmerica—
3LatinAmerica—
4ItalianAmerigo—
5Proto-Germanic*Amalarīks—
6Proto-GermanicHaimarīksHenry
7Proto-Germanicrīksking, ruler
8Proto-Celticrīxsking
9Proto-Indo-Europeanh₃rḗǵsking, ruler
10Proto-Indo-Europeanh₃reǵ-to straighten, to right oneself; right; just

via Japanese 南

StepLanguageWordMeaning
1Japanese南the south; a southerly, south wind; to go south
2Middle Chinese南—

via Japanese 北

StepLanguageWordMeaning
1Japanese北north; the North; a northerly, north wind
2Chinese Mandarin北—
Every word from Proto-Indo-European h₃reǵ- →Every word from Proto-Indo-European h₃rḗǵs →Every word from Proto-Celtic rīxs →
南北アメリカ — Etymology, Origin & Word History | Etymology Explorer