Jainism is the answer that matches the Bihar-specific fact asked in the question. Vaishali, located in the Vaishali district of Bihar, is considered the birthplace of Vardhamana Mahavira, the 24th and last Tirthankara of Jainism. Mahavira was born in Kundagrama (Vaishali) in 599 BCE (traditionally accepted date). Vaishali is also significant for Buddhism — the Second Buddhist Council was held here after the death of the Buddha, and it was also the birthplace of the courtesan Amrapali, who later became a disciple of Buddha. Vaishali is often called the world's first republic because it had a Lichhavi clan-based democratic system of governance. However, the question specifically asks about its association as the birthplace of the 24th Tirthankara, which firmly points to Jainism. Buddhism is associated with Vaishali for the Second Buddhist Council and Amrapali's story, but Mahavira's birth makes it primarily a Jain sacred site. Hinduism and Sikhism have no specific Tirthankara tradition. This distinction between Vaishali's Buddhist and Jain connections is a very common source of confusion in exams. The alternatives Buddhism, Hinduism, Sikhism may be valid Bihar-related terms, but they do not satisfy the complete relationship asked here. Revise the complete pair ‘The ancient city of Vaishali, considered the world's.