It's a given if you maintain an extreme euro-centric point of view. That's hardly the kind of citation you've asked of me. Anyone truly familiar with history will know this claim is a delusion of euro-centric historians and probably of many Romans. However, even they asked where their silk came from.
I did study history in college and for years after. I stand by what I said and a glance and the few (of many possible) sources that I linked will show I'm correct. The known world extended far beyond the limits of the Roman Empire and if adrildno knows history, he knows this. Are you saying Alexander the Great didn't reach India when Rome was just a city state? The Romans fought wars with the Parthians and traded with India. I'm not going to spend my time developing an exhaustive bibliography for people that don't know these basic facts. At least read the second link in post 20.