Why did Zhu Rong and Gong Gong fight?

The story is recorded in Huainanzi: "In the past, the four poles were abandoned, Kyushu was cracked, the world was covered, the land was not placed, the fire was not extinguished, and there was more than water. Wild animals eat people, while birds prey on the old and the weak. So Nu Wa refined five-color stones to make up the sky, broken claws and four poles, killed the black dragon to help Jizhou, and accumulated reed ash to stop lewd water. " In this way, "Heaven supplements it, the four poles are positive, the yin is exhausted, the Jizhou is flat, the cunning dragon dies, the people's livelihood improves, and it is famous for future generations." Biography of Historical Records of Huang San records: "Nu Wa's home ... In its last years, governors had industrialists, who were wise and punished, dominating instead of being king. They fought with Shui Mu and Zhu Rong, overwhelmed and angry, but their heads were not touched by landslides. Nu Wa is refining five-color stones to make up the sky, breaking the shackles is enough to establish four poles, and collecting reed ash to stop drowning and help Jizhou, so the land is peaceful and natural, and the old things will not change. " The meaning of these two paragraphs is the same, that is to say, in the era of the flood, Vulcan Zhu Rong and Vulcan finally fought because of some contradictions. Finally, Vulcan Zhu Rong defeated Vulcan * * *, and Vulcan * * * felt very ashamed and resentful because of the defeat, so he ran into the western hills, but he didn't expect this to be a disaster. The hill is a pillar supporting the sky, and the big pillar between heaven and earth is broken. Mankind is facing an unprecedented disaster. Nu Wa felt very painful when she saw such a huge disaster, so she decided to mend the sky to end the disaster. She chose five-colored stones, melted them on the fire, mended the hole in the sky with this slurry, and then cut off four feet of a chinemys reevesii as four pillars to support half of the collapsed sky. Nu Wa also captured and killed the man-eating black dragon, protecting people's safety. Finally, in order to stop the flood, Nuwa also collected a large number of reed grass, burned it into ashes and buried it to stop the flooding everywhere. Through the efforts of Nu Wa, the heaven was finally mended, the land was filled, the flood stopped, and the man-eating monster disappeared. But after all, this catastrophe left its mark. Since then, the sky is still tilted to the northwest, so the sun, moon and stars naturally return to the west, and because the ground is tilted to the southeast, all the rivers gather there. The so-called "the sky is not satisfied with the northwest, and the land is not satisfied with the southeast."