In China, it is 4697. On the Islamic calendar, it is 1418. To Hindus, it is 5099. More than 40 calendars are ticking around the world today, most of them counted from the reign of a monarch or birth of a prophet. While Americans party themselves silly in Times Square on Dec. 31, hundreds of millions of people in China will greet the New Year with a collective yawn.
Round numbers are very poetic.
But culturally there are many calendars. 2000 is not a religious number, it's a psychological number. And there are going to be people who say 2000 is meaningless, psychologically. Calendars have evolved incrementally over the past 6,000 years. The phases of the moon gave us the lunar month.