Eusebius is the main source for this martyrdom. The details became known to him through letters written by the Christian community in Lyon in Gaul to the churches of Asia and Phrygia. It is understood that the particular details pertaining Blandina's trial were transcribed into these letters from the official transcripts.
Although date is somewhat doubted, most scholars accept it.
Martyred in Lyon, CE 177, Blandina may have moved to Gaul from Asia. She was reportedly tortured for her devotion. Along with many fellow martyrs, she was subjected to several days of ordeals in the gladiatorial amphitheater on the final day of which she was killed by a beast.
Eusebius. Historia Ecclesiastica, Book 5