The vast majority of limited trade during pre-industrial times is due to the inefficiency of (i.e. cost) of long range transportation. A single modern cargo sh

The vast majority of limited trade during pre-industrial times is due to the inefficiency of (i.e. cost) of long range transportation. A single modern cargo ship can carry more cargo in a single voyage than an entire years worth of the entire medieval world's cargo fleets. And at a price that is few orders of magnitude cheaper (per ton). Not that it mattered since production of everything was, by today's standards, a few orders of magnitude less efficient. It's often difficult to fully grasp how inefficient and slow everything was in pre-industrial times until you dig into the details.