What is the meaning of Ninety-nine bends of the Yellow River in the world?

The so-called 99 bends of the Yellow River in the world is just a generalization to describe the twists and turns of the Yellow River in the Hetao Plain. Just like there is a song "the world's Yellow River 99 bends" is not really only 99 bends, Chinese people love to use "nine" and "nine" multiples to describe more.