Book 6, chap 19 (17) ― The nation's of Scythia and the countries on the eastern ocean
"He adds also, that under the direction of Pompey, it was ascertained that it is seven days' journey from India to the river Icarus, in the country of the Bactri, which discharges itself into the Oxus, and that the merchandize of India being conveyed from it through the Caspian Sea into the Cyrus, may be brought by land to Phasis in Pontus, in five days at most. There are numerous islands throughout the whole of the Caspian sea: the only one that is well known is that of Tazata."
Analysis:-
1. "The question of finding a route between the Oxus valley and India has been of concern historically. A direct route crosses extremely high mountain passes in the Hindu Kush and isolated areas like Kafiristan. Some in Britain feared that the Empire of Russia, which at the time wielded great influence over the Oxus area, would overcome these obstacles and find a suitable route through which to invade British India – but this never came to pass.[29]"
https://en.m.wikipedia.org/wiki/Amu_Darya
2. "A direct trade route from Kashmir through the historical region of Bactria (modern-day northern Afghanistan and surrounding areas) did not exist in the way one might imagine, as Kashmir's primary connections to Central Asia were over high Himalayan passes, notably via the <Karakoram and <Zoji La passes to Ladakh and then towards Yarkand, not directly through the geographical region of Bactria. However, Kashmir was a key node on the larger Silk Road network, which extended into Central Asia and regions beyond, including areas that were once part of Bactria. Goods from Central Asia, such as Bukharan silks and Russian-made cottons, would enter Kashmiri markets via this extended network, while Kashmiri goods like textiles were sent eastwards along the Silk Road."
The only tributary on left bank is Panj. River Icarus is unknown. From above two, it shall be clear that it is not possible even now to cross merchandise from india to river oxus, forget about it being done in 7 days.
