how to delete the entire history before a certain commit

Hi,

I noticed, that this post never arrived :-( . So here again.

We have a git repository, whose size we want to reduce drastically due to frequent clone operations and a slow network connection.

The idea is following:

* archive the git repository just in case we really have to go back in
history.

create a new git repository, which shall only contain last month's activity.

all changes before should be squashed together. It would be no problem if the very first commit remains unmodified.

I made some attempts with git rebase -i

but I always encounter errors. Example error is a cherry pick which can't be applied.

Is git rebase the correct way to delete en entire history section or are there smarter ways to do this? (e.g. create a new repository with last months state as starting point and some 'magic' to replay from this point on with all branches and merges_

thanks for any suggestion.