Long before Santa Claus, caroling and light-strewn Christmas trees, people in medieval Europe celebrated the Christmas season with 12 full days of feasting and revelry culminating with Twelfth Night and the raucous crowning of a “King of Misrule.”

Christmas in the Middle Ages was preceded by the month-long fast of Advent, during which Christians avoided rich foods and overindulgence. But all bets were off starting on the morning of December 25, according to Anne Lawrence-Mathers, a historian at the University of Reading in the UK where she specializes in medieval England, a period that runs roughly from the 5th century A.D. to 1500 A.D.

“Once Christmas Day came around, if you had the stamina, then you were expected to eat, drink, be merry, dress up, play games, go dancing around the neighborhood for 12 days solid before you collapsed in a heap,” she says.

In the Middle Ages, the holiday began in earnest before dawn on Christmas morning with a special Christmas mass that signaled the official end of Advent and the start of the feasting season, which ran from December 25 through January 5.

The degree of Christmas decadence depended on your social status, but Lawrence-Mathers says that most people would at least have a pig slaughtered in November and salted and smoked in preparation for Christmas bacon and hams.

In the countryside, wealthy lords of the manor were expected to give their tenant farmers at least 12 days off from their labors and also to serve them a festive meal. It’s hard to know exactly what was on the menu, but in the "The Goodman of Paris," a text written in 1393, the author outlines the required courses for a “special feast.” The meal began with a course of pasties, sausages and black pudding; then four courses of fish, fowl and roast meats; and a final course of custards, tarts, nuts and sweetmeats.

Medieval royalty took the art of Christmas feasting to a different level. For a Christmas dinner held at the Reading Abbey in 1226, King Henry III ordered 40 salmon, heaps of venison and boar meat, and “as many lampreys as possible.” Henry V, who ruled in the early 1400s, included even more exotic delicacies on his Christmas menu like crayfish, eels and porpoise.

“One thing that comes out very clearly is that drinking was as important as eating, if not more so,” says Lawrence-Mathers, noting that ale and spiced cider were the drink of choice for the commoners, while the lords and royalty gulped downs casks of wine. In just one year, Henry III ordered 60 tuns of wine for Reading Abbey with one tun being equal to 1,272 bottles.

Maybe it was a byproduct of all the drinking, but dress-up games and role reversals were a surprisingly big part of medieval Christmas celebrations, some of which were holdovers from earlier pagan customs around the Winter solstice.

For example, mumming was a popular Christmas pastime in medieval English villages. Mummers would dress up in animal masks or disguise themselves as women, and then go door-to-door singing festive folk songs and telling jokes. Some mummers did it for fun, while others expected a few coins or small gifts in exchange.

The animal masks may have been related to another strange Christmas tradition practiced by the royalty, in which revelers would parade through the feasting hall wearing whole animal’s heads (cooked, thankfully) and singing special songs. The most common costume was a boar’s head, which Lawrence-Mathers says was replaced with a wooden boar’s mask in later periods.

In the middle of the 12-day party was the Feast of Fools, held on January 1, in which priests, deacons and other church officials were given a brief license to be silly. Role reversals were popular, in which the lowly subdeacons delivered sermons, and things sometimes got out of control. According to a 15th-century French account condemning the practice:

“Priests and clerks may be seen wearing masks and monstrous visages at the hours of office… They dance in the choir dressed as women, panders or minstrels. They sing wanton songs. They eat black puddings… while the celebrant is saying mass. They play at dice… They run and leap through the church, without a blush at their own shame.”

Celebrated on the night of January 5, Twelfth Night or Twelfthtide was a holiday all its own in the Middle Ages and represented the culmination of 12 days of merrymaking and mischief. Shakespeare likely penned his famous comedy Twelfth Night as a play to be performed on Twelfth Night, hence the cross-dressing heroine and practical jokes.

The centerpiece of Twelfth Night was the bean cake, a rich fruit-filled cake in which a tiny dried bean was hidden.

“Whoever got the slice of cake with the bean in it was ‘king’ for the night and could give people silly forfeits [penalties] which they had to obey,” says Lawrence-Mathers. Another term for the king was the “Lord of Misrule,” who had the power to upend social hierarchies and demand embarrassing tasks from authority figures like parents, schoolmasters and lords.

Twelfth Night was the climax of the nearly two weeks of feasting, drinking, dressing up and rule-breaking that characterized medieval Christmas.

Oddly enough, the 12 days of Christmas also held special significance for the medieval pseudo-science of prognostication, says Lawrence-Mathers.

Priests pored over texts called “prognostics” that explained the Bible-centered practice of interpreting signs from nature—including storms, high winds and rainbows—to predict the weather for the coming year and also foretell important events.

“The idea being that God sent signs for those who could read them, and that the 12 days of Christmas were a special time,” says Lawrence-Mathers.

If it was sunny and clear on Christmas Day, for instance, that was a sign that the spring would be warm and mild, leading to successful crops and good overall health. However, strong winds on Christmas Day signaled a bad year for the rich and powerful.