Could you clarify what, exactly, you are asking, and perhaps why? Do you want to know what Hitler, specifically, knew, or more what the state of Chinese historical knowledge was in early 20th century Germany? The latter is, potentially, answerable, but the former...

We have only a few places to look for definitive knowledge of what Hitler thought, and to start with the Table Talk, Hitler is essentially silent about Bronze-Age China, with only the briefest mention in passing that under the Confucian system in Ancient China "The poorest young village lad would aspire to become a mandarin" (Page 97). That is it. He makes one more brief foray into later Chinese history noting when talking the threat of the 'Asiatics' towards Europe to state that "[w]e understand now why the Chinese shut themselves up behind a wall to protect themselves against the eternal attacks of the Mongols", and then going on to note that while there is an impulse to follow China's example and build a wall, history shows that walls don't work since:

The fact is that a too great feeling of security provokes, in the long run, a relaxation of forces. I think the best wall will always be a wall of human breasts!

As for Mein Kampf and the Second Book, well... These is simply nothing. Any mention of China refer to his own times, not ancient history.

So simply put, we don't know what Hitler knew...