Draper traces Marx's use of the term "oriental despotism" to Hegel, and points out that the Soviet and Chinese "refutations" of the theory of oriental despotism were tied to (a) the attempt to straitjacket all history into a theory of identical stages (feudalism-capitalism-socialism, etc.) and (b) above all, the desire to prove that there could be no class rule which wasn't based on *private* property.
On the other hand, we have Wittfogel, who used the theory of the asiatic mode of production not only as a stick to beat the Soviet bureaucracy with (following and exaggerating Karl Kautsky in this regard) but as a refutation of Marxism itself, accompanied by some rather extravagant theoretical pretensions.
Draper's "Note" is 28 pages long, and followed by an 8-page one dealing separately with Engels and Oriental Despotism.