1. Story of Yanxi Palace
It tells the political situation of Qianlong's harem. Qianlong is one of the most successful emperor and also the most well-known. The fl is his third (if I remember right) empress and the mother of an emperor. The fiction is probably the relationship between fl and Fuca Fuheng. The other parts including Fuheng's son Fu Erkang is Qianlong's son may be true.
2. The Princess' Man
It tells the romance between the daughter of Sejo of Joseon (the son of King Sejong: the founder of Hangul) and the son of prime minister of the opposite party. King Sejong choose his oldest to become emperor not only becuse he's the oldest but also because he helps Sejong created Hangul (adapted from Hanzi-Chinese alphabet). Sejo accept the decision but after his brother died, he rebel. Most parts of the drama are real including him killing the child emperor (his nephew) and killing a lot more including her niece's husband and the prime minister. But his daughter's romance may be true but also may not be true.