Pattern [country name] + 人 = '[nationality] person' is fully productive in Chinese: 美国人 American, 法国人 French, 阿富汗人 Afghan. The country name 阿富汗 (Āfùhàn) is itself a phonetic transliteration of 'Afghan'.
memory
阿富汗 is purely phonetic: 阿 (ā) for 'A-', 富 (fù, 'rich') for '-fu/-f-', 汗 (hàn, 'sweat') for '-han'. Then + 人 'person'. The character meanings ('rich' + 'sweat') aren't literal — sound only.
