Gaelic Ireland was initially pagan and had an oral culture. Inscription in the ogham alphabet began in the protohistoric period, perhaps as early as the 1st century. The conversion to Christianity accompanied the introduction of literature, and much of Ireland's rich pre-Christian mythology and sophisticated law code were preserved, albeit Christianized. In the Early Middle Ages, Ireland was an important centre of learning. Irish missionaries and scholars were influential in western Europe, and helped to spread Christianity to much of Britain and parts of mainland Europe.