This expression would be used in french to describe a place where something is plentiful, or from where something originates.

Off the top of my head an example is France sometimes being referred to as

le pays des droits de l’Homme

in reference to France’s historical role in human rights.

However, as in the example you provided, “le pays” does not have to refer to an actual country, and can just refer to an area or even abstract poetic concepts.

For instance, sleep is sometimes called

le pays des rêves

Furthermore, many children’s books may refer to “au pays des géants” or such examples, referring to some land containing giants.

In terms of translating it, I would use the expression “the land of” as opposed to “the world of”.

Common expressions are “the land of the free”, to talk about the United States, “the land of the rising sun” to talk about Japan, or “the land of giants” to refer to my above example.

In terms of other usages of “le pays”:

• at its most basic, just means “the country”
  

  L’Espagne, c’est le pays où je vais le plus souvent en vacances.

• sometimes can refer to where someone is from
  

  Je retourne au pays => I’m going back to my hometown/home area

• can be used to describe visiting the country side/various parts of a country
  

  Le week-end dernier, je suis allé voir du pays

Pays translates the English word "land"¹ in

le pays des larmes…

Lewis Carrol’s Alice’s Adventures in Wonderland has been translated into French as Les Aventures d’Alice au pays des merveilles.

The various translations of Le Petit Prince I have consulted all translate

C’est tellement mystérieux, le pays des larmes.

as

It is such a mysterious place, the land of tears.[eg]

Laurent PetitGirard’s piece of ballet music Le Pays des larmes for Le Petit Prince has retained the translation "The Land of Tears".

To respond to OP’s comment to @NicoMezeret that "tears here are more of a concept then a place", I’ll point to the song by English singer Julian Cope "When I Walk Through the Land of Fear", where there is no reference to a place whatsoever, but to a state of mind.

"Land" is used in place of "country" when the word refers not to the political, administrative or geographical entity but to an emotional one. Let’s think of "the Land of Plenty" to designate the US (Film by Wim Wenders), "Land of Fear" to designate here a district of Cairo, "land of fear and loathing" used here for England.

A popular catchphrase nowadays is au pays des bisounours². Le pays des bisounours being a land peopled with rather dumb-witted and gullible creatures.

Alain Juppé veut prouver qu’il "ne vit pas au pays des Bisounours"

Cyberattaque : l’édition vit-elle au pays des Bisounours ?

^{1 See wikipedia definition 7.
2 Les Bisounours: The Care Bears.}