Mountain is related to Terrain. Desert is a type of Terrain. you are likely to find Mill in/at/on Desert. 
People is related to Transport. Transport is related to Horse. Horse is related to Burden. Burden is related to Tax. 
Mountain <--RelatedTo--> Terrain <--IsA-- Desert <--AtLocation-- Mill 
People <--RelatedTo--> Transport <--RelatedTo--> Horse <--RelatedTo--> Burden <--RelatedTo--> Tax 