Without discouraging further discussion, there have been a few similar questions asked before that you may find interesting:

• We have a section in our FAQ dedicated to it

• But since the FAQ section is a little sparse there's more questions here

• "Were there any "new millennium" celebrations in the year 1000AD? - November 2012

• "Did people in 999 AD celebrate the new millennium? Were there any doomsday predictions similar to Y2K?" - November 2013

• "The Year 1000: Critics (Modern and Medieval)?" - March 2014

• "Were there any "millennium hysteria", doomsday prophecies or such at the shift 1000 AD?" - November 2014

• ["What was the sentiment about the date ticking over from 999AD to 1000AD? Was there some kind of fear/panic/theological significance similar to our tech scare Y2K? Any notably large celebrations?"] (https://www.reddit.com/r/AskHistorians/comments/2pljpl/what_was_the_sentiment_about_the_date_ticking/) - December 2014

• "Did people do anything special to celebrate the year 1000 A.D.?" - August 2015

Hopefully this helps :)

I don't know about the Christian world, but in the Muslim world (or at least the Ottoman Empire), the year 1000 of the Islamic calendar (1591/2 CE) was thought of in apocalyptic terms. Many believed that it would bring about the end of the world, and many of the economic and political hardships of the end of the sixteenth century were attributed to it. When it became clear that the world was not going to end, interest died down. It however remained a popular starting year for history books written in the seventeenth century.