Update: See the comment below on the history of the day.
Yennayer is an Amazigh celebration in Algeria and other places where there is a significant berber population – it is currently under way as it is usually celebrated between 12-14 January of each year. My admittedly quick lazy searching did not prove me otherwise: I wonder whether it is the oldest celebrated day in the world, is it? It has been celebrated since the Amazighs’ victory over Ramses III in Tlemcen in 950 BC, 2960 years ago. Read more about it here and here. The French Wikipedia has a more comprehensive entry in French.
The Kabyle region have been campaigning for a long time for an official recognition of the day. Recognising it as an important cultural event in Algeria is surely a great asset to the country.