そんなだから A little help for translation

Question

I need some help to figure out how can I translate そんなだから.
It must quite vague because it seems to lack a noun after そんな (such as 時、本、etc.). If it had such nouns I could understand it like "at this kind of time, "this kind of book"). If I were to adapt it a little, would "It's for this reason." I think literally would be "That's why".
The action of this manga is that it's about saving someone from a villain. The ones going against this villain is a group of friends, they are fighting with all they got in order to save their captured friend.
そんなだから-That's why/This is our reason (for fighting), (to save our friend).
I hope you can understand...I don't know if I explained it so well.

Answer 1

According to a dictionary, そんな/こんな is a na-adjective (形容動詞). It usually works attributively (i.e., directly modifies the following noun) and means "such" (そんな人 = "such a person"). It sometimes works predicatively and means "(... is) like this/that".

• 毎日こんなだ。
  Things are like this every day.
• へえ、もう彼はそんなですか。
  Oh, is he already like that?
• 君がそんなだと我々は勝てない。
  If you're like that, we won't be able to win.

This こんな/そんな refers to what's mentioned in the previous context or what's in front of the speaker/listener.

Therefore, そんなだから naturally means "Because it's like that", "Because you're like that", etc.