Zone is a synonym of Territory. Territory is related to Country. 
Expedition is related to Trip. Trip is related to Extend. Extend is related to Edge. Edge is related to Horizon. 
Zone <--Synonym--> Territory <--RelatedTo--> Country 
Expedition <--RelatedTo--> Trip <--RelatedTo--> Extend <--RelatedTo--> Edge <--RelatedTo--> Horizon 