Introduction:
Both Buddha and Mahavira were influential spiritual leaders who lived during the 6th century BCE in ancient India. They both belonged to the religious tradition of Jainism, which emphasized non-violence and the pursuit of spiritual enlightenment. In order to understand the connection between Buddha, Mahavira, and the Mahajanapadas, it is important to have a brief understanding of what Mahajanapadas were.

Mahajanapadas:
- The term "Mahajanapada" refers to the sixteen ancient kingdoms or republics that existed in northern India during the 6th century BCE.
- These Mahajanapadas were characterized by their political and administrative structures, and they played a significant role in shaping the socio-political landscape of ancient India.

Identification of Buddha and Mahavira's Mahajanapada:
- Out of the given options, the Mahajanapada to which Buddha and Mahavira belonged is the Vajji Mahajanapada.
- The Vajji Mahajanapada was located in present-day Bihar and its capital was Vaishali.
- It was one of the most powerful and prosperous Mahajanapadas during that time, known for its republican form of government.
- Buddha was born in Lumbini, which was located in the Shakya republic, a part of the Vajji Mahajanapada.
- Mahavira, the founder of Jainism, was born in Kundagrama, which was also a part of the Vajji Mahajanapada.

Significance of Vajji Mahajanapada:
- The Vajji Mahajanapada was known for its strong sense of democracy and political organization. It had a confederate form of government where the power was shared among several republican tribes.
- The Vajji Mahajanapada played a crucial role in promoting the spread of Buddhism and Jainism.
- Both Buddha and Mahavira delivered their teachings in the Vajji Mahajanapada, and their ideas found resonance among its people.
- The Vajji Mahajanapada was also a major center of trade and commerce, attracting merchants from various parts of India and beyond.

Conclusion:
In conclusion, Buddha and Mahavira both belonged to the Vajji Mahajanapada, which was a powerful and influential republic in ancient India. The Vajji Mahajanapada played a significant role in the spread of Buddhism and Jainism, and its political and administrative structures contributed to the socio-political landscape of ancient India.

Page number 4.3 of ancient and medieval india by poonam dalal dahiya says that lumbini is in koshala mahajanapada.. please clarify it