In Sangam Period, Biryani was referred as 'Oon Thuvai Adisil'
'Oon Thuvai Adisil' - "Oon" refers to meat, "thuvai" is a blend, and "Adisil" is a cooked meal.
The word 'biryani' came into usage at a later date. They mention that when the Timur came to India in 1398, the food of Biryani came to India. But Biryani food was eaten by Tamils and others during the Sangam period.
Reference : Oon Thuvai Adisil
Oon Thuvai Adisil - English translation
Sangam Period : https://en.wikipedia.org/wiki/Sangam_period