So far, the Library at Alexandria and Arabic numerals have been mentioned, and both are clearly of other than Arabic origin. What other wonders of the Arabic world do you think were suppressed?
And for the earlier rocket and A-bomb thing, I don't believe there are any history books that fail to credit Werner Von Braun for his role in rockets, nor do they fail to mention that some of the folks on the Manhattan Project were European expatriates. The note from Einstein to FDR that started that effort is certainly well known.
If you think all is propaganda, why do you bother posting? And if all you present is a claim akin to 'the truth is out there, but hidden' you just end up sounding like one of the tin-foil hat brigade.
The Nazi had developed the bomb before us. Many thing came out after the fall of the Berlin wall.