Bharatvarsh,
See if we can find somewhere "A History of Dashnami Naga Sanyasis" By Jadunath Sarkar. Book is not there on http://dli.iiit.ac.in/ nor on googlebook. I am hopeful that book will throw more light on historical aspects of Adi Sankar.
Meanwhile, I am reading a Jaina book that certainly mentions life and works of a monk known by name Bodhkirti or Dharmakirti, a great scholar and Brahman-turned-Jaina-turned Bauddha monk, who lived in the times of Bhagwan Mahaveer, in a city of 'Palashpuram' on the bank of Saryu river, and prepared several works on Bauddha/Jaina philosophy. So this may support what you had quoted about the time of Dharmakirti. Sankara may have very well quoted him, rather than Bodhakirti/Dharmakirti of 7th century. (But since I have not studied what he has quoted and in which context, I am not concluding anything - just pointing out that multiple scholars with the same name/title have been commonly found in Bauddha/Jaina traditions.)
(The story of this great scholar Bodhakirti is very interesting. I will post that later.)
See if we can find somewhere "A History of Dashnami Naga Sanyasis" By Jadunath Sarkar. Book is not there on http://dli.iiit.ac.in/ nor on googlebook. I am hopeful that book will throw more light on historical aspects of Adi Sankar.
Meanwhile, I am reading a Jaina book that certainly mentions life and works of a monk known by name Bodhkirti or Dharmakirti, a great scholar and Brahman-turned-Jaina-turned Bauddha monk, who lived in the times of Bhagwan Mahaveer, in a city of 'Palashpuram' on the bank of Saryu river, and prepared several works on Bauddha/Jaina philosophy. So this may support what you had quoted about the time of Dharmakirti. Sankara may have very well quoted him, rather than Bodhakirti/Dharmakirti of 7th century. (But since I have not studied what he has quoted and in which context, I am not concluding anything - just pointing out that multiple scholars with the same name/title have been commonly found in Bauddha/Jaina traditions.)
(The story of this great scholar Bodhakirti is very interesting. I will post that later.)