Mulan (2009)

Both movies are about a girl disguising as a boy. Both movies are directed by Jingle Ma. Both movies are based on famous classic Chinese tales.

Both are epic Chinese historical wuxia war movies. Both movies star Vicki Zhao as a kickass noble lady.......................

Both FLs disguise as men and join the army, becoming a general. Both MLs discover the FL's gender when they accidentally see her taking a bath.

Both productions have Chen Kun as male lead, accompanied by cross-dressing strong female lead. While one of them focuses more on fighting/action and the other one focuses on politics, they both showcase women who are good at their, seemingly male-only, job.

Both have a strong FL who disguises herself as male and a military ML who learns her secret early on but hides it for her.

I've read that the series were based on the 2009 film, it was daebak

Both are telling the legendary story of Hua Mulan and how she went into the military in place of her father and became a great solider that sacrificed a lot for the safety of her homeland.

Both films are about historical wars inspired by real events and old tales. They involve two great heroes – who by cunning and courage – saves their nation from hostile foreign forces. Willing to sacrifice themselves, they're selflessly fighting for what's important; to achieve lasting peace and to protect their country, and countrymen. The movie Mulan, though, have elements of romance and a stronger fokus on friendship.