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Inca

Noun (singular and plural) and adjective. NGS prefers the traditional spelling, Inca, the spelling most familiar to readers.

Some modern scholars prefer Inka, which they consider a more accurate transliteration. If the newer spelling is used, it should be explained, or the old spelling given in parentheses on the first mention.

The spelling of other place-names is also changing:
  Cuzco
Huari
Nazca
Tiahuanaco
to
to
to
to
Cusco
Wari
Nasca
Tiwanaku