The folk lore behind a nine tle fox is for every hundred years it lives it's gains a tale, so a fox with nine tails is a thousand years old, at this point the fox changes color's to either silver, white or gold. The demon fox in Naruto is based on the Koren fox spirit which are depicted as evil monsters. In Japanese mythology fox's are Benevolant or Malevolent creatures. So yeah Naruto uses alot of Asian folk lore as sorce to draw from.