Big Rock is the first foal and first winner of the unraced Hardiyna (Sea The Stars), a half-sister to the winner Harannda (Invincible Spirit).

Second dam Harasiya (Pivotal) won the Gr.3 Silver Flash S., was second in the Gr.2 Debutante S. and third in the Gr.1 Moyglare Stud S. She is a half-sister to Harzand (Sea The Stars), a champion and sire who won the Gr.1 Derby and the Gr.1 Irish Derby.

Third dam Hazariya (Xaar) won the Gr.3 Athasi S. Besides Harasiya and Harzand she bred three more black-type performers: Haripour (Shamardal), a Listed winner placed at Group 3 level, Hazarafa (Daylami), winner of the Listed Finale S. and dam of Hazapour (Shamardal), successful in the Gr.3 Derby Trial and the Gr.3 Amethyst S., and of the Listed winner Haparanda, and the Group 3-placed Haziyna (Halling), grandam of the Group 3-placed Haziym. Her daughter Hazaraba (Oasis Dream), a winner, is the dam of the Listed-placed Haziya.

Hazariya is a half-sister to Hazarista (Barathea), winner of the Gr.3 Blue Wind S. and third in the Gr.1 Irish Oaks and the Gr.1 Yorkshire Oaks, and to the Listed-placed Hidden Brief, the dam of Emily Upjohn (Sea The Stars), winner of the Gr.1 British Champions Fillies & Mares S. and the Gr.1 Coronation Cup. This is also the family of Hurricane Lane (Frankel), a triple Group 1 winner including the Gr.1 Irish Derby, the Gr.1 Grand Prix de Paris and the Gr.1 St Leger, and Seal Of Approval (Authorized), another winner of the Gr.1 British Champions Fillies & Mares S.

Hardiyna has a 2-year-old colt by Ten Sovereigns named Hazard and a filly foal by Australia.