Well, the book was originally published in England under the name Ten Little N⸺s, and in that edition the location was named “N⸺ Island.”

For obvious reasons, that title was considered unsuitable for sale in America, so American editions were renamed to And Then There Were None, and the island and poem were changed to reference (depending on edition) Indians or soldiers instead. Most editions these days have settled upon soldiers.

Incidentally, Wikipedia mentions one use of the phrase “our black brothers” that only makes sense in the context of the original naming.