Within a few weeks, a vast land area was mapped out, with only a couple of dark patches in between. These patches were mostly villages.
Most villages did not have anything interesting to warrant caravans to pass through them. Not to mention, these villages' citizens mostly didn't have the resources to head out at all, so they were mostly living in isolation.
This was the case in most villages. Where else would they find a place like the Terran region, primarily made of villages, but had such active traffic exchanged between them?
Of course, heading out often was only possible for the weaker territories because of the infrastructure and the network Alterra created. Otherwise, it was a costly endeavour. In Towns, it was definitely a mercenary team-worthy trip, which was why they'd never run out of jobs.
Another reason why Tambai and Tanod hadn't attempted to head out before this was…money and strength.
