Vatsa ［跋蹉］ (;  Bassa): One of the sixteen great states in ancient India. Vatsa was located south of the Ganges River in what is today the Indian state of Uttar Pradesh. Its capital was Kaushāmbī. In Shakyamuni Buddha’s time, Udayana was king of Vatsa and a follower of the Buddha. At that time, the three powerful countries of the Ganges Valley—Magadha, Kosala, and Vatsa—were in conflict with one another. Magadha was located to the east of Vatsa, and Kosala, to the north of Vatsa across the Ganges River.