An alternative to submodules is subtree merging. Subtree merging is a strategy that can be used when performing merges with Git. The strategy is useful when merging a branch (or, as we'll see in this recipe, another project) into a subdirectory of a Git repository instead of the root directory. When using the subtree merge strategy, the history of the subproject is joined with the history of the super project, while the subproject's history can be kept clean, except for commits intended to go upstream.