Bharatvarshji, very interesting indeed. I have not paid attention to it before, and always took 788AD for granted. However if memory serves me right at the moment, this date of Adi Shankar is not based purely upon Shankar citing Dharmakirti. Fortunately there are various other sources of being able to corroborate the time of Shankar.
1. His travels to various kingdoms, and addressing various Kings of his time. Some of the famous addresses were made to the Kings of Kashi, Kamrup, and Ujjain.
2. In his Digvijay Abhiyan, he engaged various philosophers from all types of schools in all corners of India - from Kanchi to Ujjain to Patiliputra to Nalanda to Kamrup to Srinagar.... Fortunately, many of those philosophers were very well established in history, Sankar's Shastrartha being big event, we can find a lot of 'trail'. Having several independant references can easily fix the timeline. Jaina records are most useful, and more trustworthy than Bauddha.
3. Being a prominent personality that he was, we should find some mention in the massive literature that was created by Kalidasa, Bhartrihari, if he happened to pre-date Kalidasa or Bhartrihari, and other writers.
4. There are various legends associated to him. Like his act of Kaya-Parivartan or Pran Parivartan, where he left his body and entered the body of a king (from Kamrup?) who had died recently. In kings body he lived for a month with 2 queens of that king, to learn about kaam shastra that was needed for a Shastrartha he had to have with SArada Devi. (He composed a wonderful analysis of Kaam Bhasya). Now the date of this king can be found out, though we shall have to rely upon a legend which is though highly trusted by his followers.
5. This is a subjective point, and I admit may be due to bias. His Bhasya/TIkA of different Upanishads and Shastras is very 'fresh', so to say, or 'new age'. The very expression, style, phrases, are so "new", and mark these apart from BC thought-process and literature. But this can not be counted upon.
All said, like the timeline of Gautama Buddha, that of Adi Sankar is not settled then? Hmmm...
1. His travels to various kingdoms, and addressing various Kings of his time. Some of the famous addresses were made to the Kings of Kashi, Kamrup, and Ujjain.
2. In his Digvijay Abhiyan, he engaged various philosophers from all types of schools in all corners of India - from Kanchi to Ujjain to Patiliputra to Nalanda to Kamrup to Srinagar.... Fortunately, many of those philosophers were very well established in history, Sankar's Shastrartha being big event, we can find a lot of 'trail'. Having several independant references can easily fix the timeline. Jaina records are most useful, and more trustworthy than Bauddha.
3. Being a prominent personality that he was, we should find some mention in the massive literature that was created by Kalidasa, Bhartrihari, if he happened to pre-date Kalidasa or Bhartrihari, and other writers.
4. There are various legends associated to him. Like his act of Kaya-Parivartan or Pran Parivartan, where he left his body and entered the body of a king (from Kamrup?) who had died recently. In kings body he lived for a month with 2 queens of that king, to learn about kaam shastra that was needed for a Shastrartha he had to have with SArada Devi. (He composed a wonderful analysis of Kaam Bhasya). Now the date of this king can be found out, though we shall have to rely upon a legend which is though highly trusted by his followers.
5. This is a subjective point, and I admit may be due to bias. His Bhasya/TIkA of different Upanishads and Shastras is very 'fresh', so to say, or 'new age'. The very expression, style, phrases, are so "new", and mark these apart from BC thought-process and literature. But this can not be counted upon.
All said, like the timeline of Gautama Buddha, that of Adi Sankar is not settled then? Hmmm...