Caubīsī

The wheel of time runs down through six aras and back up through six, forever. In each half-turn, twenty-four Tīrthaṅkaras arise in Bharat — no more, no fewer. Ours ran from Ṛṣabha to Mahāvīra.

So the tradition speaks of three caubīsīs at any moment: the atīta, just past; the vartamāna, ours; and the anāgata, to come. Scripture names all seventy-two, but gives heights, lifespans and intervals only for ours — which is why only ours can be drawn in descent.

In Mahāvideha Kṣetra, which the wheel does not turn, Tīrthaṅkaras are always present instead — the twenty viharamāna, outside every caubīsī.