Migrate data from a 4.7 system to another ECC6 system

hi all

we have a project to reduce nb of SAP instances, so instead of upgrading our old 4.7 system, we will move the sites from this old one to a more recent ECC6 ERP system-

So ,I was wondering whether there is a quick way to "export data" from 4.7  (for a given organization) and "import" into the new ECC system ?

any recommendation ?