Kunti and the Pandavas were living in "agyatavaasa" (living incognito) after they escaped from the murder plot (Kunti suggests they be incognito to avoid further problems from the Kauravas). During their stay at Ekachakra or kaiwara (in West Bengal), they came to know of a demon, Bakasura, who troubled people by eating members of their village and their provisions. The powerful Bhima brought his might to the fore and killed Bakasura, much to the delight of the villagers and when Bhima killed Bakasura, it was confirmed that Duryodhana, Kichaka, and Jarasandha would be killed by Bhima. Bhima, Duryodhana, Jarasandha, Kichaka and Bakasura were born in the same cosmic phase. As a result of that, the first of these strong people to kill another, the other three would eventually die. Besides the renowned sages like Vyasa, only Krishna and Sahadeva knew this.