एवं परम्पराप्राप्तमिमं राजर्षयो विदुः। स कालेनेह महता योगो नष्टः परन्तप ॥

evaṁ paramparā-prāptam imaṁ rājarṣhayo viduḥ sa kāleneha mahatā yogo naṣhṭaḥ parantapa

This, handed on down the line, the King-Sages knew. This yoga by great efflux of time decayed in the world, O Parantapa.

In plain words: Krishna says wise kings passed this teaching down from one to the next. But over a very long time it was lost in the world.