According to Peter Heather, a historian at King's College London, during the Roman Empire, the German tribes east of the Rhine River (the area the Romans called Germania) produced no coins of their own but used Roman coins instead: Although no coinage was produced in Germania, Roman coins were in plentiful circulation and could easily have provided a medium of exchange (already in the first century, Tacitus tells us, Germani of the Rhine region were using good-quality Roman silver coins for this purpose).
a. What is a medium of exchange?
b. What does the author mean when he writes that Roman coins could have provided the German tribes with a medium of exchange?
c. Why would any member of a German tribe have been willing to accept a Roman coin from another member of the tribe in exchange for goods or services when the tribes were not part of the Roman Empire and were not governed by Roman law?