Biruni is obviously using the past tense That s all I can gather from the sentence So it can be any time before his time which would be pre Turkic anyway But then again to answer your question we d have to read the entire passage of the Biruni quote to investigate the full chronological context It will take me a while after May the soonest before I can go to Austin where they have a copy of the Athar al Baqiyah to shoot a picture of the page and post it on the talk page for all to view I m currently stuck with commitments to attend to