Every Veda has a secondary Veda, Upaveda.
Dhanur Veda – the knowledge of the art of war is integrated into the Rig Veda.
Sthapatya Veda – the knowledge of architecture is integrated into the Yajur Veda.
Gandharva Veda – the knowledge of music and dance is integrated into the Sama Veda.
Ayur Veda – the knowledge of life is part of the Atharva Veda.