I read a question on Information Security about how Facebook could know recommendations of friends by just a phone number.
The answer to that question explicitly details that the more probable scenario is one in which the friends of the phone contact shared the information to Facebook.
So let's start there. Let's assume a phone number is in a contact list "123-4567"
At this point, before a friend syncs to Facebook. All this is a number, not a name, not an address.
You can state here that Facebook holds phone numbers (because Facebook users allow them to) to assist with the Suggested Friends / People you may know feature.
With you interacting with Facebook in anyway
https://www.facebook.com/legal/terms
Special Provisions Applicable to Users Outside the United States
We strive to create a global community with consistent standards for
everyone, but we also strive to respect local laws. The following
provisions apply to users and non-users who interact with Facebook
outside the United States:
You consent to having your personal data transferred to and processed
in the United States.
If you are located in a country embargoed by the United States, or are
on the U.S. Treasury Department's list of Specially Designated
Nationals you will not engage in commercial activities on Facebook
(such as advertising or payments) or operate a Platform application or
website. You will not use Facebook if you are prohibited from
receiving products, services, or software originating from the United
States.
Certain specific terms that apply only for German users are available
here.
Definitions
By "Facebook" we mean the features and services we make available,
including through (a) our website at www.facebook.com and any other
Facebook branded or co-branded websites (including sub-domains,
international versions, widgets, and mobile versions); (b) our
Platform; (c) social plugins such as the Like button, the Share button
and other similar offerings and (d) other media, software (such as a
toolbar), devices, or networks now existing or later developed. By
"Platform" we mean a set of APIs and services (such as content) that
enable others, including application developers and website operators,
to retrieve data from Facebook or provide data to us. By "information"
we mean facts and other information about you, including actions taken
by users and non-users who interact with Facebook. By "content" we
mean anything you or other users post on Facebook that would not be
included in the definition of information. By "data" or "user data" or
"user's data" we mean any data, including a user's content or
information that you or third parties can retrieve from Facebook or
provide to Facebook through Platform. By "post" we mean post on
Facebook or otherwise make available by using Facebook. By "use" we
mean use, run, copy, publicly perform or display, distribute, modify,
translate, and create derivative works of. By "active registered user"
we mean a user who has logged into Facebook at least once in the
previous 30 days. By "application" we mean any application or website
that uses or accesses Platform, as well as anything else that receives
or has received data from us. If you no longer access Platform but
have not deleted all data from us, the term application will apply
until you delete the data.
In terms of the registration specifically, since you never finished the process then the user you registered isn't validated. Why would Facebook store dirty data since 2006?
With actual requests of data use this form
https://www.facebook.com/help/contact/166828260073047
