Millenium means 1000 years.
The next millennium year will be in the year 3000.
The year 1399 was in the second millennium.
It will be the third millennium, being its final year.
The year zero was the year before the first millennium.
The 2nd Millennium began in the year 1001.
The year 3000 will be the next millennium.
The second millennium.
A millennium
The start of the second millennium AD was 1001, and the final year of the second millennium was 2000.
An actual Millennium year is always a leap year, so it is 366 days.
A millennium is 1,000 years for example 2000 is the year of a new millennium
2017 is in the third millennium AD.