Answer

In Jain tradition, the war between Krishna and Jarasandha is associated with Rajagriha — also known as Rajgir in present-day Bihar, India.

Explanation

Jarasandha was the powerful ruler of Magadha, whose capital was Rajagriha. Krishna and Balram are described in Jain tradition as important figures in the Jain universal history connected with the lives of the Tirthankars and other great personalities.

The conflict with Jarasandha is generally connected with the region of Magadha, especially Rajagriha/Rajgir, because that was Jarasandha’s seat of power.

Takeaway

The location most closely associated with Krishna’s conflict with Jarasandha is Rajagriha/Rajgir, Bihar, the ancient capital of Magadha.