Munisuvrat Swami (Munisuvrat Nath) was born in Rajgir (Rajgriha), in the historic Hari‑ vansh realm of the Rajgir kingdom in present-day Bihar. This birth place is consistently stated in Jain traditional accounts and is mentioned in Jain Knowledge summaries as Rajgriha (Rajgir). If you want to read a concise treatment, you can check the Jain Knowledge page on the topic.