How is Dark Messiah connected to Heroes of Might and Magic?

You're talking nonsense, sir. Dark Messiah of Might and Magic was released noticeably earlier than the Gold Edition of Heroes 5, which included the Heroes of Might and Magic 5 Dark Messiah mod as a bonus. The standard edition of Tribes of the East did not include this mod. This was created by some foreign enthusiast based on the action game, not the other way around.