YOU SAID:
The island of Taiwan, formerly known as Formosa, was inhabited by aborigines before the 17th century, when Dutch and Spanish colonies opened the island to mass Han immigration.
INTO JAPANESE
台湾の島は、以前はフォルモサとして知られていましたが、オランダとスペインの植民地が漢族移民のために島を開いた17世紀以前に、原住民が住んでいました。
BACK INTO ENGLISH
The Taiwanese island was formerly known as Formosa, but aborigines lived there before the 17th century when the Netherlands and Spain colonies opened the island for Han Chinese immigrants.
INTO JAPANESE
台湾の島は以前はフォルモサとして知られていましたが、オランダとスペインの植民地が漢民族の移民のために島を開いた17世紀以前に、原住民が住んでいました。
BACK INTO ENGLISH
The Taiwanese island was formerly known as Formosa, but aborigines lived there before the 17th century when the Netherlands and Spain colonies opened the island for Han Chinese immigrants.
That didn't even make that much sense in English.