Ancestor Netherworld River was sealed in the Netherworld River because he had violated the heavenly laws. He was sealed in the Netherworld River by the immortals to prevent him from causing greater harm to mankind. To be more specific, Ancestor Netherworld River had once violated a great heavenly law, that is, he did not respect the souls of others and casually played with the souls of humans, causing many human souls to suffer torture and pain. Therefore, the immortal decided to seal Ancestor Netherworld River in the Netherworld River so that he would never be able to escape punishment. As for the people who harmed Ancestor Netherworld River back then, there might be many because the background of Ancestor Netherworld River's story was relatively wide. It might involve many different characters and events. However, because Ancestor Netherworld River was sealed in the Netherworld River, he could not know who these people were and could not take revenge.