Repositories: How to move content from one repository to another one

Goal

The content from the source repository should keep the Git history.

Steps

1. Create a new repository with the content to move:

git clone [e-mail]:AlexRogalskiy/<source-repository>.git
cd <source-repository>
git-filter-repo --path <path-to-extract> \
 --path <path-to-extract> \
 --path <path-to-extract> \
 ...

1. Publish that new repository

2. Add it as a remote repository to the target repository:

git clone [e-mail]:AlexRogalskiy/<target-repository>.git
cd <target-repository>
git remote add new-content <url>
git fetch new-content

1. Merge the extracted content:

cd <target-repository>
git merge --allow-unrelated-histories new-content/master
# (adapt the content if it's necessary)
git push origin master

1. Remove the published repository (step 2)

2. Create a pull request into the source repository to remove the extracted content