During the period of Mahajanapadas, Mathura was the capital of

The correct answer is Surasena. The Mahajanapads were the 16 kingdoms that existed between the 6^th - 4^th century BCE in Northern ancient India. The Surasena Mahajanapada corresponds roughly to today's Brij region of Uttar Pradesh, Haryana, and Rajasthan. It had Madhura or Mathura as its capital.