Thus received by succession, this yoga was known by the king-sages. But with the great passage of time, oh Arjuna, here it was lost.

The paramparā — transmission from teacher to disciple — preserved yoga among the rājarṣayaḥ — kings who were also sages.

But kālena mahatā — the great time — erodes everything, even sacred knowledge. Naṣṭaḥ — lost, destroyed — indicates not total absence but corruption, loss of original meaning. Knowledge needs periodic renewal.