@Klaxun so mumming is this premedieval cultural behaviour you see in europe, it permeates pagan ritual and as christianity asserts itself it continues to be allowed as this way of letting off steam (much like christmas or a strange medieval idea of The Purge). Mumming is the act of being someone else, breaking your vow with god for a brief time and inhabiting someone else in a more root urge way. People could make a lot of money while mumming which is a sin, and the idea of earning more than your lot is very outside of what a peasants role in life is. So you wear masks and disguise yourself while you do so. You have the rise of festivals where everyone drops their social roles and laws are suspended with a king of fools being elected to proclaim new decrees of law to be followed during. You could fuck with whom you wanted, marriage ceased to be recognised, and if you or your partner became pregnant with another then after the festival you two would raise the child as your own (as christ rule was restored).
This is all hugely sexually charged of course, and so european royalty and the courtier classes begins to adopt it too, as masquerades. Parties where the same rules apply (everyone fucks and doesnt know who anyone else is), but done on a far higher budget. Extravagant outfits to show off your plumage, mock ideas, make statements and compete. France very big into it.
Then France colonizes west africa and brings with it the concept of Masquerade which becomes popular there mixing with cultural events and religious ceremony.
Then Slavery, and you get Black Masquerade coming to the Americas, so you get New Orleans with mardi gras, and voodoo, as well similar cropping up across the east coast.
Masquerade Ball becomes Grand Rag which becomes Drag Ball