The Four Sources of Sira

In arabic, the word is shama il. A number of early authors wanted to describe the propheism and they wrote books about his description. The most famous book of delail is called te la il nobu of al behai. And so by reading the taris of macka and medina, we extract sira. To this modern people have added a sources that were not found in moslem lands. This is very difficult and rare. But there is a new genre of research in academia and in islamic studies here in america and western world. What did the romans say about the arabs at the time? What did the persians say?