Changing blog date order in MySQL

I may be looking at this the wrong way, but what I am trying to do is this:

Bringing over some posts from a different system, and want to manipulate the creation date to get the sort order and archive dates OK to start with.

Looking at MySQL with PHPAdmin at the content then a page I create today gets the value 1215513038 in created.

This doesn’t seem to be a Gregorian serial date (today would be 733231)

Can anyone advise how the date is made up, so I can create dates in the past and change them?

Thanks

Mark

The date is stored as a unix timestamp.

There are several unix timestamp converters online.
http://www.onlineconversion.com/unix_time.htm

superb, just what I needed - thanks!