Mao DID NOT, nor did anyone with whom he was associated, ever give rise to the phrase 'Third Wrold.' The words were coined by a Frenchman and goes back to 1952.

"The situation is pretty confused, all right, which is about par for the course in matters etymological. I've heard the phrase attributed to the French agronomist Rene Dumont, but the most convincing story credits French demographer Alfred Sauvy, who is said to have coined tiers monde in 1952. The archaic tiers is used instead of the modern troisieme to suggest a parallel to tiers etat, the Third Estate, which came into currency during the French Revolution. The Third World is thought to hold a position vis-a-vis the First and Second Worlds (the developed capitalist and Communist countries, respectively) comparable to that of the Third Estate (the commoners) with the First and Second estates, i.e., the clergy and the nobility."