Historic Christmas
Christmas day was originally known as Christ's Mass, a special day to commemmorate Christ's birth. The day was preceded by Advent, a four week period of penitence which started on Advent Sunday, and finally ended on Christ's Mass eve. Advent was a solemn time and prepared the citizenry for the advent of Christ, his coming.
Christmas day itself isn't actually the real day of Christ's birth. Nobody really knows when Christ was actually born, we don't know the day or even the year. He may have been born in 4BC or even 1AD. We think he was born in April or May because Christ's Mass was originally observed at this time. It wasn't until 350 AD and Pope Julius 1 that the date was changed to the 25th December. In those days the old traditions and festivals of the Romans were still practiced, and this included the winter solstice festival of Saturnia. This was a time of great revelry and human sacrifice which the church wanted to eradicate. The simple solution was to christianise the festival.
By all accounts Pope Julius was only partly successful, and the traditional 12 days of festivities continued despite the wishes of the church. Finally the Council of Tours (567 AD) adopted 12 days as the official period of festivities. These 12 days of Christmas were to start on Christmas day and continue till the 6th of January, the feast of Epiphany.
Epiphany is the day Christ manifested himself to the Magi who are said to have arrived in Bethlehem from the east on this day. The magi brought with them gifts of gold, frankincense and myrrh.