Subversion in general uses an internal copy operation to create branches or tags. The good thing is that a copy operation creates some kind of link between the copy source and desination file (or directory). This is especially helpful for following the history of copied objects - you can follow the history of such an object (file or directory) as if there was no copy in between.
If you do not want to see the history of a file before the copy process you can tell this subversion. Just use
svn log --stop-on-copy
on your branch and you will not see history before the creation of the branch. Using Subversive you can choose this option in the History view. Please refer to the Subversive Users Guide:
Subversive User Guide, TeamSupport with SVN, SVN History View, see "Stop on copy".