Yes, there was a time-travel novel called Feng Qingge. The title was "The Genius of the Unparalleled Mad Queen." It was a fantasy romance novel. The story was about a top-tier assassin from the modern Dark Assassin Organization who transmigrated to Black Tortoise Country and was reborn as the useless Fifth Miss Feng Qing Ge, the direct descendant of the Feng family, the number one family in Black Tortoise Country. Then, she rose to power and fought against the gods and demons, standing at the top of the world and overlooking the common people. I hope you like my recommendation. Muah ~