MUCH of Viet-Nam's history before 200 B.C. is shrouded in legend —but so is much of Europe's past beyond the Mediterranean basin. A kingdom known as Van Lang and, briefly, Au Lac, seems to have existed between 500 and 207 B.B., 1 apparently covering most of what is today China's Kwang-tung Province and North Viet-Nam. The latter, as will be seen, has been a border zone more than once in Viet-Nam's long and stormy history.