which historical circumstances gave rise to the missionary efforts of the saints?

Answer 1

I do not know exactly what you are asking; what time period or its context. But I will answer it in the way I precieve it.

There is the first instance of 'sainthood' and that was immediately following Christ's ascension when the first Christians were persecuted by the Romans. The persecutions led to martyrdom. The blood shed from the martyrs which described in old manuscripts as filling the streets for their Faith led to the great time in history which rose up the great "Doctors' of the church. I always found that interesting; the blood of the martyrs and then the Doctors...