Believed to be a reference to the coronation of George the V as Emperor of India.
The following is a quote from the Debussy biography written by Debussy's colleague, E. Robert Schmitz: "In 'Le Beau Voyage', Rene Puaux, while describing the Durbar ceremonies for George V, as Emperor of India, speaks of 'the hall of victory, the hall of pleasure, the garden of the sultanesses, the terrace for moonlit audiences'..."