Rishabhdeva era means the time‑reckoning that starts from the nirvana (moksha) of Bhagwan Rishabhdeva (Ādināth), the first Tirthankara. In Jain tradition his nirvana occurred in a very ancient time of the current avasarpinī (descending) half‑cycle, far beyond human historical dating. Therefore, unlike Vīra Nirvana Samvat (which begins from Bhagwan Mahāvīr’s nirvana), the Rishabhdeva era is not used as a practical civil calendar today.

• Digambar and Śvetāmbara traditions: Both accept that Rishabhdeva is the first Tirthankara and that his era lies in an extremely ancient period; no exact BCE/C.E. date is assigned. Both revere his moksha at Aṣṭāpada (Mount Kailāsa).

For simple reading on Ādināth/Rishabhdeva and this ancient timeframe, see:

• “When era of Ādināth Bhagwan started”
• “Lord Rishabh Dev’s life history”
• “Aṣṭāpad – The Lost Tirth” (regarding his moksha‑kshetra)