1800 Milenio Extra Añejo Tequila was first introduced to celebrate the turn of the millennium in 2000. It doesn't carry an age statement, but to be considered extra añejo the youngest tequila in the blend must be aged for at least three years.
1800 Tequila is a brand owned by Casa Cuervo, producers of the world-famous Jose Cuervo line of tequilas. According to their marketing materials, the name refers to the year tequila was first produced (this doesn't appear to be even remotely true), and the 100% blue agave product is branded as a more premium tequila than others in the family. The 1800 range includes the standard blanco, reposado, and añejo, as well as a coconut tequila and a handful of specialty extra-añejo bottles.