I think Flashman is more-or-less real history. Sure, he isn’t actually involved in all the battles and things, but the historical accuracy in terms of characters (except Flashman), settings, and dates, is supposed to be superb.
Guy Gavriel Kay has some decent books, notably A Song For Arbonne and the Sailing To Sarantium series. One’s about 12th century Europe, and the Sarantium series is Byzantine.
I recently read The Years of Rice and Salt, by Kim Stanley Robinson, and I highly recommend it. It’s a reimagining of history starting with the premise- what if the Black Death had wiped out the West, and the powers were the Islamic Middle East, China, and India?
The story starts in about 1450 and finishes in 2002.It’s retold through a group of characters who are reborn endlessly, and interact with each other in every lifetime. It’s the plot device that makes the story hang together as one very long lifetime shared by a group of friends.
Very interesting, and splendid writing.