Short answers, pulled from the story.
The Volga trade route was a medieval trade corridor connecting Northern Europe and Northwestern Russia with the Caspian Sea via the Volga River. Traders traveled from settlements near Lake Ladoga south through Novgorod, along the Volga, through the Khazar Khaganate, and across the Caspian to caravan routes leading to Baghdad. The route functioned from at least the end of the 8th century until it lost importance in the 11th century.
Traders moving south carried furs (including beaver, sable, squirrel, and black fox), honey, and enslaved people. Merchants returning north brought Arab silver dirhams, silk, and crucible steel from the Middle East. Iranian lusterware, Syrian, Egyptian, and Mesopotamian ceramics, and chess also traveled north through these same connections.
The Volga Bulgars were a seminomadic confederation, described in the sources as cousins of today's Balkan Bulgarians, whose two cities Bulgar and Suvar lay east of what is now Moscow. They occupied a central position on the route, trading with Viking peoples from Rus and Scandinavia to the north, with the Byzantine Empire to the south, and with Russians and fur-selling Ugrians. From the early 10th century onward, the Caspian-bound slave trade ran through Volga Bulgaria rather than the Khazar Khaganate.
Ahmad ibn Fadlan traveled to Volga Bulgaria as part of a diplomatic delegation from Baghdad in 921-922 and recorded detailed observations about Rus traders. He described their ritual prayers to carved wooden idols before trading, their practice of sacrificing goats or cattle after successful deals, and a system by which a man's wife received a gold ring for every 10,000 dirhems he accumulated. Ibn Fadlan also noted that the Rus retained Scandinavian customs regarding weapons, ship burials, and religious sacrifices.
Viking raiders captured people across Europe and transported them south via the Volga to sell to buyers in the Abbasid Caliphate, or via the Dnieper to Byzantine buyers. The trade ran from the 8th through the 11th centuries, with the Volga route carrying enslaved people through Ladoga, Novgorod, and eventually through Volga Bulgaria and Khwarazm to the Samanid slave market in Central Asia. Arab dirham hoards found in Scandinavia, including the Spillings Hoard and the Sundveda Hoard, contain coins dated from at least 786 through 1009 and represent the silver paid for these goods.
The Volga trade route lost importance in the 11th century primarily because silver output from the Abbasid caliphate declined, removing the main economic incentive for the long journey to Baghdad. The Christianization of the Viking nations of Denmark, Norway, and Sweden also made it infeasible to continue slave raids against Christian Europeans and sell them to Islamic buyers. Trade weight shifted to the Dnieper route leading to Byzantium, and after a failed expedition around 1041 led by Ingvar the Far-Travelled, no further Scandinavian attempts to use the Baltic-Caspian passage are recorded.