Upaplavya is a city mentioned in Mahābhārata. It was situated beside the capital of Virāṭ, the king of Matsya. After the twelve years̍ exile and one year̍s ajñātavāsa, Pāṇḍava(s) came to Upaplavya, and here the son of Arjuna, Abhimanyu, got married to Uttarā, daughter of king Virāṭ. On the occasion of this marriage, all the friends and well-wishers of the Pāṇḍva(s) assembled there. They were– the Vṛṣṇi(s) under the leadership of Kṛṣṇa, Andhaka, and the Bhoja kings, the king of Kāśī, Drupada, Śikhaṇḍī, the warrior-sons of Draupadī, and Dhṛṣṭadyumna. In fact, Upaplavya is that place where the Pāṇḍava(s), on the occasion of the wedding of Abhimanyu and Uttarā, got assembled, and planned to reclaim their kingdom, by war or by peace. It should be kept in mind that after a long separation of thirteen years, the Pāṇḍava(s) openly met their friends and allies, in this place. So it was natural that the future plans for reclaiming their lost kingdom should be undertaken here.. Due to its geographical location as well, the city of Upaplavya strategically became very important for conducting the war. Perhaps it was a satellite township situated near the frontier area of the Virāṭ kingdom, for we come to know from the Udyogaparva that — when the Pāṇḍava(s) came to live in Upaplavya, the inhabitants of the city were glad, considering themselves secure and protected by the Pāṇḍava(s)–
nodvignāḥ paracakrāṇāṃ vyavasanānām.

We think that this enemy was the Kuru state, because the kingdom of Virāṭ was located at the northern boundary of Hastināpura, for instance, Jaipur of modern Rajasthan is situated at the frontier of Delhi. Frontier-clash was perhaps rampant, so the inhabotants were happy to have the pāṇḍva(s) as their protectors. It was out of that pleasure, that when Kṛṣṇa was going to Hastināpura from Upaplavya, for the purpose of peacemaking embassy, the inhabitants of Upaplavya gathered by the roadside to see him–
upaplavyādathāgamya janāḥ puranikasinaḥ.
pathyatiṣṭhantaḥ sahitā viṣvaksenādidṛkṣyā.

When the peacemaking embassy failed, Vāsudeva Kṛṣṇa came back from Hastināpura to Upaplavya and informed the Pāṇḍava(s) that Duryodhana and his ministers had renounced all proposals and possibilities of peace. So the war was uinevitable. And for conducting the battle of Kurukṣetra, the importance of Upaplavya was manifold, because the Pāṇḍava(s) used this place both as the war-camp and supply line. The location of Upaplavya– as it was near the capital of the kingdom of Virāṭ , as well as in a frontier position, and also it was equally close to Kurukṣetra– gave it a strategic significance. The Pāṇḍava(s), armed for the battle went to Kurukṣetra, and Draupadī and the other women, seeing them off to the battlefield. came back to Upaplavya. From Udyogaparva it is also known that before setting out for the battle, the Pāṇḍava(s) protected the city with so many soldiers so that during their absence, the women and the wealth of the family remain safe and secured. In this context it is further known that there were several fortresses in the city of Upaplavya and it was surrounded with canyons and high walls–
upaplavye tu pāncālī draupadī satyavādinī
sahastrībhirnivavṛte dāsīdāsasamāvṛtā.
kṛtvā mūlapratīkāraṃ gulmaiḥ sthāvarajañgamaiḥ
skandhāvāreṇa mahatā prayajuḥ pāṇḍunandanaḥ.

So it can be said that Upaplavya was a fortess that was used by the Pāṇḍava(s) as a safety cam. Sage Vedavyāsa visited the Pāṇḍava(s) at Upaplavya, before the battle. He also gave a direction, saying that Dharma (righteousness exists where Kṛṣṇa exists. And wherever Kṛṣṇa is, there must be victory.

upaplavye maharṣirme kṛṣṇadvaipāyano̍vravīt

yato dharmastataḥ kṛṣṇo yataḥ kṛṣṇastato jayaḥ.

In light of another incident, Upaplavya has acquired a special significance in the whole account of Mahābhārata. After the mass slaughter in the battle of Kurukṣetra, the Kuru dynasty got destroyed almost in entirity, but Parīkṣit was born of the womb of Uttarā, sired by Abhimanyu. In Sauptika parva, it is heard from Vāsudeva Kṛṣṇa that some righteous Brāhmaṇa prophetically announced the birth of Parīkṣit, in Upaplavya itself. That profecy came to be true: overcoming the fatal influence of Aśvatthāmā̍s Brahmaśira astra, Parīkṣit was born as the preserver of the Kuru dynasty.

There have been disagreement among scholars about the present location of Upaplavya. However, most of them agree on one thing, that Upaplavya was located somewhere at the frontier of Rajasthan and Hariyana. Some have considered Upaplavya to be the capital of Matsya. But this may not be right, because the capital of ancient Matsya-land was Virāt pattana or Virātnagara. However, in Mahābhārata itself, there is evidence that Upaplavya was near Hastinapura. As an ambassador of peace, Vāsudeva Kṛṣṇa reached Hastināpura from Upaplavya within two days. .