During the Viking age, people from Scandinavia traveled across eastern Europe to the Black and Caspian Seas, where they traded, raided, and served as mercenaries in the armies of Byzantine Emperors, Khazar Khans, and various other rulers.
How did they get there?
You've all probably heard an answer that goes something like, "They sailed down the rivers." But as I just learned from River Kings, a 2021 book about the Viking Age by Norwegian/British archaeologist Cat Jarman, this was actually very difficult. There were many portages, some of them miles long, a few of them dozens of miles long. Jarman reports that while many teams of Swedish, English, and Russian adventurers have tried to voyage from the Baltic to the Black Sea via the rivers, none have succeeded; all eventually gave up and loaded their boats on trucks for substantial segments of the route.
So most likely the journey from the Baltic to Kiev involved a lot of walking. Not that the Vikings were afraid of walking; one of the mercenary armies that fought on the Caspian Sea got there by sailing to the eastern end of the Black Sea and walking across the Caucasus. But it seems unlikely that very many ships were ever sailed and dragged from the Baltic to the Black Sea. Jarman says the consensus among archaeologists today is that the trade from the Baltic to the navigable parts of the Dnieper and Volga Rivers was carried out in shallow-bottomed rowboats. And rather than dragging their boats across the longer portages, they may simply have left one boat or fleet behind, carried their goods overland – or made them walk, since the most valuable part of what they sold south was slaves –and then loaded onto another set of boats when they reached the next lake or river.