Does Weatherford go into the relationship between the Mongols and the Turks? My understanding is that a primary reason for interest in finding a sea route to the Orient was that the fall of Constantinople to the Turks had disrupted an existing trade over the silk road to the Black Sea, and that access had been tightening for decades as the Turks took over more and more of Anatolia and the Black Sea shore.

"It is not necessary to have hope in order to persevere."