Translation of vorgeschichtlich

In the meantime I am listening to some Spanish CDs. They are intended for the car, but no one can tell you when to listen to it, how many times and how often. Please understand that I work a lot.
However, if you are able to link to us from another major site (school site, language site, maybe even a good private site), I will be able to convince my colleagues to make an exception and upload your lessons.
In order to see it you have to complete a lesson. I attached a screenshot. I did not place any rating there, so that it will not demotivate some of the users, especially the fresh beginners.