The burden of proof is on you. What a nice twist from you. If darius has the tech and mean to plough thru a canal across the suez during his time.Well, considering the fact that the Europeans were rediscovering mathematical theorems that we had discovered several centuries ago before the 15th century, that's entirely possible. After all, they hadn't discovered the canal before Napoleon!
And I'm not the one that needs to prove my claim. You're the one that's denying a historical fact. So, the burden of proof is on you, not me.
He would achieved more than what genghis khan accomplished.