Pho originated in the early 20th century in north Vietnam, and was popularized throughout the world by refugee after the Vietnam War. Because Pho origin are poorly documented, there is disagreement over the cultural influences that led to its development in Vietnam, as well as the etymology of the name.The Hanoi (northern) and Saigon(southern) styles of Pho differ by noodle width, sweetness of broth, and choice of herbs. (Wikipedia)