Who says there's no evidence? One author or researcher might take such a position; others would challenge it. That's how scientific discourse works.
The question you ignore or overlook is, what constitutes evidence? Only someone with an axe to grind says there's zero evidence against the position he is taking.
Judging from your readiness to make such categorical statements and defend them as "the truth," I suspect that you have read a book you found convincing. Read a few more and you'll be far less certain. Become an actual expert with a degree in this or any field, and you'll readily admit how much you don't know.