Mong ethnic people live mainly in Pa Co and Hang Kia communes (Mai Chau). In addition to the special features in the costumes and the highland specialties such as making corn wine using the leavened yeast, Meo broccoli, pounding Day cakes on Tet holiday has been a typical traditional culture and customs of Mong ethnic people.

When Spring comes, Mong people’s villages in the communes of Hang Kia and Pa Co (Mai Chau district) are bustling with the sound of pounding "banh day” (sticky rice cake). Every Lunar New Year (Tet), local people gather together to make the soft and delicious cakes from steamed sticky rice.

The end of lunar February and the beginning of lunar March is when the weather becomes warm with the spring buds after the days of sleeping in the cold weather. That is when the black ant colonies converge on their nests to lay eggs. The young ants' eggs with the aroma are round and milky like the rice grains, which are a special kind of cake filling for people to make the quite unique and very delicious and attractive cakes – the cakes from ants’ eggs.