Yudhishthira, the eldest of the five Pandava Prines, was born to Kunti by the grace of Yama. His actions were free form passion and prejudice. He come to be considered the very embodiment of Dharma and was respectfully referred to as Dharmaraja.

Yama, the awe-inpiring God of death, is also revered as the Lord of Justice. According to Hindu belief, all living beings reap the fruit of their actions after death. Yama administers justice to all the beings brought before him. Since he metes out justice strictly according  to Dharma,he is called Yamadharma. Who else could test Yudhishthira but Yamadharma?  Yudhishthira emerged from the ordeals a stronger soul.