There are many funding opportunities for international cooperation and the internationalization of research.
On the website for BMBF International Cooperation (Kooperation International des BMBF) you can take the first steps to finding opportunities for world-wide collaboration. There you can orientate yourself if you would like to start networking or even start a specific project.
Over the BMBF International Office you can search for region-specific funding opportunities for international collaboration preparatory measures.
You can also find country-specific funding programs over the DFG.