I agree, India and probably Central Asia. Though, there are latter sources on the manofacture of wootz. I can´t still put my hands on books like
Persian Steel and
Persian Metal Technology. Jens is decades ahead of me on this readings. But I think we cannot be conclusive about iranian wootz production, and archaeometallurgy is still in it´s beginnings. I still do not read Manouchehr´s book..too expensive for me, taking on account the caravan post services EUA-México additional cost.
Jens, thank you very much for your input.