In Jain Dharma, the reason moksha is only up to the end of 4th āra (in our Bhārat Kṣetra) and not in 5th āra is based on the nature of the time‑cycle (kālchakra).

Very simple explanation:

1. Time is in cycles (kālchakra)

Each half‑cycle (avasarpiṇī / descending, and utsarpiṇī / ascending) has 6 aras. We are now in 5th āra of avasarpiṇī in Bhārat Kṣetra. ( jainknowledge.com)

1. Role of 4th āra (dukhama‑sukhamā)

- In our present avasarpiṇī, all 24 Tirthankars (including Mahāvīr Bhagwān) take birth in the 3rd and 4th āra. ( jainknowledge.com) - The spiritual atmosphere in 4th āra is still sufficiently strong for: - Tirthankars to exist - Kevalīs (omniscient beings) to arise - Souls to attain moksha from Bhārat Kṣetra - Mahāvīr Bhagwān’s nirvāṇa happens at the very end of 4th āra; shortly after that, 5th āra starts.

1. What changes in 5th āra (dukhama)

According to Jain texts and tradition: ( jainknowledge.com) - No new Tirthankars are born in Bhārat Kṣetra. - No new kevaljñān arises here. - Therefore, no final moksha is attained from Bhārat Kṣetra during 5th (and 6th) āra. - Religion (dharma) continues in a weakened form; people can still practice, but the exact conditions required for final liberation here are no longer present.

1. So why is moksha said to be “till 4th āra”?

- Because the last kevalī and last liberated souls of this Bhārat Kṣetra in this half‑cycle attain moksha around the border of 4th–5th āra. - After that point, the remaining karmas and spiritual capacities of beings here are such that no one can complete the full path to moksha in this very life in Bhārat Kṣetra. - Both Digambar and Śvetāmbara accept this principle: - 4th āra: Tirthankars, kevalīs, moksha possible here. - 5th āra: no Tirthankars, no kevalīs, no moksha from Bhārat Kṣetra. ( jainknowledge.com)

1. Is moksha totally stopped now?

No. The rule is only for this place and this era: - In Mahāvideh Kṣetra, Tirthankars are present even now and moksha is still going on there. - By doing right faith, right knowledge and right conduct here, one creates causes for future birth in Mahāvideh (or in a future suitable āra), and then attains keval‑jñān and moksha there. ( jainknowledge.com)

In short:

• Up to end of 4th āra in Bhārat Kṣetra, the spiritual conditions allow moksha here.
• From 5th āra onward, in Bhārat Kṣetra specifically, those conditions disappear, so moksha no longer occurs here, though it continues in Mahāvideh and will re‑appear here in future cycles.

You can read a simple explanation of Jain kālchakra and the six aras here: “Understanding Jain Kalchakra (Time Cycle)”