Source of HPL's coordinates for Great Race ruins?

[Donald G. Davis]

Does anyone know why HPL selected "20o 3' 14" South Latitude, 125o
0' 39" East Longitude" for the location of the Great Race's city? I've
looked at that location in Google Earth, and seen a vast desert of
shifting dunes on rocky soil just as described in "The Shadow Out of
Time." The site looks perfectly appropriate, but how did Lovecraft learn
about it?
--Donald Davis

[Pinku Basudei]

On Thu, 17 Dec 2020 04:50:08 +0000

Post by Donald G. Davis
Does anyone know why HPL selected "20o 3' 14" South Latitude, 125o
0' 39" East Longitude" for the location of the Great Race's city? I've
looked at that location in Google Earth, and seen a vast desert of
shifting dunes on rocky soil just as described in "The Shadow Out of
Time." The site looks perfectly appropriate, but how did Lovecraft learn
about it?
--Donald Davis

I'm guessing now but perhaps because the site was remote and devoid of any other major historical settlements?