How did the church convert barbarian peoples to Christianity?

The Mediterranean served as the highway over which Christianity spread to the cities of the Roman Empire. Christian teachings were initially carried by all types of converts, but they were often spread into the countryside and into areas beyond the borders of the empire by those who had dedicated their lives to the church, such as monks. Such missionaries were often sent by popes specifically to convert certain groups. As they preached to barbarian peoples, the missionaries developed new techniques to convert them.