It is not known exactly when Buddhism came to Vietnam. In his book Le Bouddhisme en annam des origines jusqu’au XIIIè siècle, believed to be from the 3rd century, Trần Văn Giáp asserts that Mâu Tử from China was the first person to preach Buddhism in Vietnam. Recent researchers maintain it is actually earlier (3 centuries BC), relying on stories of prehistoric heroines and personalities.