The only fact more or less accepted is that Christopher Columbus crossed the Atlantic Ocean arriving in the Americas on that date in 1492. Not the first European, the Vikings beat him to it, but believing he had found a way to India he spearheaded the colonisation of one culture by another.

In 1492, the natives discovered they were Indians, discovered that they lived in America, discovered they were naked, discovered that sin existed, discovered they owed allegiance to a king and kingdom from another world and a God from another sky, and that this God had invented guilt and dress, and had sent to be burnt alive all who worships the sun the moon the Earth and the rain that makes it wet.” Eduardo Galeano

The interpretation of what happened on that day has undergone a number of transformations, here are some of them with a little help from Wikipedia.
Originally known as Columbus Day it became a national holiday in many countries of the Americas and elsewhere as “Día de la Raza” (“Day of the Race”) and “Día de la Hispanidad” and “Fiesta Nacional” in Spain.

In the US Oct 12 is now generally celebrated as Indigenous Peoples’ Day, Argentina changed the name to Day of Respect of Cultural Diversity, Venezuela instituted the Day of Indigenous Resistance, Costa Rica the Day of the Encounter of Cultures, and so on.

“By 1900 the indigenous population in the Americas declined by more than 80%, and by as much as 98% in some areas. The effects of diseases such as smallpox, measles and cholera during the first century of colonialism contributed greatly to the death toll, while violence, displacement and warfare by colonizers against the Indians contributed to the death toll in subsequent centuries.” Wikipedia

The history of colonialism has not finished, it has continued with forms of neo-colonialism that replicate the same dehumanisation, lack of respect for cultural diversity and violence in all its forms. May this day become a day of reflection about the need to elevate the human being above all else with compassion and solidarity.