The ancient Greeks/Latins/Arabs referred to Eastern peoples, during their treks along the Silk Road; as Sinai or Sinae peoples, with the Chinese being their primary contacts. As with most anything, over time the terms became corrupted into Sino.
The clue is in the name, Sino -- to do with China.
Because they lost.
China vs Japan.
China vs Japan.
chiang kai-shek
China
Korea
yes
yes
China did with support from the U.S. and Soviet Union
The First or Second Sino-Japanese War.
China and Japan fought two modern wars (1894-1895 and 1937-1945).Cathay & Sino- refer to ancient former names of China.