Up to the time of the East Groam Plague, the Spice Route is north of that river, while the Silk Road is south of that river. Due to the plague, the Silk Road is temporarily (?) following the same route as the Spice route north of that river, south of Calishem.

When the route reaches the Qashya Mal Central Steppe, the routes diverge. The Silk Road starts heading southeast here, while the Spice Route continues east into my yet to be mapped Eastern Steppe of Qashya Mal and may fork as Spice Routes from different regions both south east and east enter that block.

GP

PS: I'll have to look at the surrounding regions to get a better idea how to answer the rest of your question...