Most dependencies are conveniently stored in its own repository called "ogredeps" for you to download.

IMPORTANT: Do NOT use the the "Download" feature from Bitbucket. It will not follow subrepositories.

Command line:

git clone --recurse-submodules --shallow-submodules https://github.com/OGRECave/ogre-next-deps

git clone --branch v2-1 https://github.com/OGRECave/ogre-next