During China’s rule of Vietnam from 111 BC to AD 980 (by medium), the Chinese introduced White Sugar Cake to the colony (via The Food Wonder). Due to a fermentation process, the cake had a sweet but sour taste. But over the years, Vietnam has completely transformed the cake from the original dense, white cake to something more spongy, leaving out the white hue instead of something much more eye-catching.
According to Epicurious, the shape of the cake we know today developed in the late 19th or early 20th century. The cake is now sweeter, fluffier and chewier than it was centuries ago and has been given a beautiful emerald green color from the infusion of pandan leaves. And, as the outlet shared, the reason for that added green color may have been a result of street vendors of the era looking to attract buyers—mainly passing children.