How did the Kyubi no Youko fox live so long?

Xuanmen's masterpiece "The Nine-tailed Fox" has lived for so long, and the nine-tailed fox belongs to the natural fox with strong vitality. Master Xuanmen is a fantasy novel created by Chen Shisan, a Hong Kong ghost screenwriter, taking Ling Hu as a sample. It tells the story that in the Eastern Han Dynasty, Xianmeng and the Wolf clan went to war one after another, and Zhang Ling, a brilliant and clever friend, went through all difficulties and obstacles and finally won the world peace.