Nodes are the unit of distance in the Renaissance Kingdoms. Slightly under half of the nodes are towns, the rest are empty between them. It is on the empty nodes that robbery takes place. On foot, a regular player can travel 2 nodes per day, and a lord can travel 3 on a horse.
Note that if two players with the same IP are on the same "Town node," or both are on any "non-town" node (i.e. both are out of towns, travelling, even if not in the same places), the Holy Inquisition evidently kicks in. This leads to a series of events, that if not properly navigated, leads to eradication. Players who share IP addresses must also avoid travelling on the same day, as this has sometimes been shown to trigger the Inquisition as well.