Dear Han Ping Fung, the history is written to introduce happened things and we do not think about its correctness while reading them. It introduces the past and is not lopsided.
Those who write the history books pick and choose which "facts" should be remembered and which "truths" should be derived from them.
But the readers of history do the same things with these history books.
100 years ago the American presidents Washington and Jefferson were remembered in order to be praised.
Today, Jefferson (like Hitler) is often only recalled to be condemned.
Facts are only as important as the truths they support. And as our truths change over time. We continually reinterpret the facts and massage them in order to support our current truths.