Find a novel that travels back to the Song Dynasty

The male lead climbed the mountain and traveled back to the Song Dynasty. However, he became a soldier on the Jin people's side and helped the Jin people fight the Song Dynasty. Later, he was caught and his face had been changed. The plot was very compact. After that, she talked about how he was going to marry the princess of that golden man. She had only seen this part and had forgotten most of it ~ This book is very old. It was probably written between 1999 and 2003, not in recent years. I hope my friends who have read it can provide some clues. I like this book, but I can't find it or remember its name.