When Prajāpati Dakṣa was lamenting for his lost children, Lord Brahmā pacified him with instructions, and thereafter Dakṣa begot one thousand more children in the womb of his wife, Pāñcajanī. This time his sons were known as the Savalāśvas.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
स भूयः पाञ्चजन्यायामजेन परिसान्त्वितः । पुत्रानजनयद्दक्षः शबलाश्वान् सहस्रशः
sa bhūyaḥ pāñcajanyāyāmajena parisāntvitaḥ | putrānajanayaddakṣaḥ śabalāśvān sahasraśaḥ
SB 6.5.24