Where does iCloud source all it's contacts from?

Question

Hi,
I have a really random thing happening on my iCloud (obviously effecting all my apple devices, iPhone 4S, Macbook Pro):
I have recently had a whole lot of old contacts turn up in my iCloud contacts. Now there weird thing is:
     - these contacts are from a cell phone I would've had about 5 years ago
     - it wasn't a smart phone, was something like a basic nokia or sony ericsson or something
     - the phone was on a different number, and a different sim card, and possibly a different network
     - the contacts weren't stored on the sim card that is currently in my iPhone
     - I didn't do any importing of any kind, they just showed up in my contacts
     - The names of the contacts are showing exactly how I put them in my old phone, ie, the name + some way to remember them (like Gary the guitar guy), so can't have been synced from anything like Facebook.
My question is, where does iCloud gather it's contact info from?? Over the years I have had hotmail, gmail, facebook, myspace, bebo, etc, does it link with them somehow?
I receive Microsoft Exchange mail and Gmail on my iPhone, but none of these old contacts show up in the contacts of these two accounts?
So confusing, and kinda creepy! Anyone know what is going on??
Thanks

Answer 1

Ohhhhh whoops just realised what I have done haha
I copied a whole lot of crap off an old hard drive onto my MacBook Pro .. included in the crap was an old backup of a vCard database I must've done ages ago .. MacBook found it and decided to import it into my contacts automatically!
As you were, Macbook ...