When the Germanic nations conquered the Roman empire, they found there the practice of writing ; and in imitation of the Romans, they set down their practices in writing and made them into codes.  The unhappy reigns that followed that of Charlemagne, the invasions of the Normans, and the internecine wars plunged the victorious nations back into the darkness from which they had come : they no longer knew how to read and write. As a result, in France and in Germany, they forgot the written barbarian laws, Roman law, and the capitularies. The practice of writing was better preserved in Italy, where the popes and Greek emperors reigned, and where there were flourishing cities and almost the only commerce there was at that time. This proximity of Italy caused Roman law to be better preserved in the regions of Gaul that had formerly been subject to the Goths and Burgundians, all the more so that this law was a territorial law and a sort of privilege. It seems likely that it was the ignorance of writing that caused the fall of the Visigoth laws in Spain ; and through the fall of so many laws, customs came everywhere into being.
Personal laws disappeared. Compensations and what were called freda were settled more by custom than by the text of those laws. Thus, as the establishment of the monarchy had seen a change from German practices to written laws, there was a return some centuries later from written laws to unwritten practices.