The only significance to the Forest of Arden is that it is the setting for the play. Shakespeare based this play on the novel Rosalynde by Thomas Lodge, and Arden is the setting of the novel as well. According to the eNotes study guide, the Ardennes, in France, would be the present-day location. Don't confuse it with the Arden Forest in England.
Lodge's novel is an example of pastoral fiction. That is, it has a rural setting and deals with romance. In keeping with the character of the novel, Shakespeare had to have the same type of setting; he couldn't place it in a city.
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