Carnival in Milevsko is based upon traditional folk plays and masked processions from Milevsko and surrounding villages. The direct predecessor of the Carnival in Milevsko was the procession with Bakus. Bakus’ the ancient god Bacchus / Dionysus, the god of wine, fertility and sacred exaltation. As an allegorical figure, he appeared in costume plays during the Renaissance and Baroque periods. He represented the period before the Lent, with its excesses and heavy eating and drinking.  His death, usually during a mock trial, foreshadows the beginning of religious fasting.

In Milevsko, Bakus is a fat, sinful and drunken countryman who walks around the city with his family and other companions, making some money during rhymed performances in pubs. The day before the ash Wednesday (or according to some traditions, on the ash Wednesday itself) he dies (from his drinking or as a punishment for his sins) and was buried into the snow on a frozen pond or a small creek. The ice often broke, and Bakus fell into the water to general amusement.

According to some sources, there was a tragic incident in 1864 when Bakus remained in the water for too long and died as a result. Authorities, who looked reluctantly at games parodying such a serious religious ceremony, banned the Bakus´ funeral. Masked processions remained to be allowed and Bakus soon returned in a modified form. Carnival gradually become a bigger and more spectacular show, each year with a different theme, the shapes of the masks changed according to fashion and popular cultural symbols of the time (Indians, Cowboys et cetera).

The tradition of the Millenium masquerade was interrupted by the First World War and by the ban by the governor Žák, who was parodied by "illegal carnival“ in 1924, for which four Milevsko citizens were convicted. The masks were restored in 1933 and then held each year except World War II. and the years 1954, 1956 and 1963 to 1968. In thirties´ it was documented by filmmakers and used as an inspiration for theatrical plays and similar celebrations on other towns. In 2018, Carnival in Milevsko was included in list of the intangible cultural heritage of the Czech Republic.