Simandhar Swami is regarded in Jainism as a living Tirthankar (a enlightened teacher) who currently dwells in Mahavideh Kshetra, a distant region of the Jain cosmology. He is not on Bharat Kshetra (our earth) but is said to be actively preaching the Jain path there. This understanding comes from Āgama-pramāṇa (scriptural authorities) and later cosmology works that describe Mahavideh Kshetra and living Tirthankaras. You may hear that his city is Pundarikgiri, in the region ruled by King Shreyans, and that his mother is Satyaki and his wife is Rukamani. However, many of these details are traditional cosmological descriptions and are treated as part of Jain mytho-cosmology rather than history in the ordinary sense. Different Jain traditions (Digambar, Shvetambar) may emphasize or phrase certain details differently, but both acknowledge the idea of a living Tirthankar like Simandhar Swami residing in Mahavideh Kshetra and guiding souls there. For devotional and doctrinal contexts, see the discussions on Simandhar Swami in Jain literature. You can read more here and here .

Note: If you want, I can share a brief, traditional summary of the Simandhar Swami narrative as found in Jain cosmology texts.