Swargarohana Parva describe how king Yudhisthira enters heaven and saw his brothers in hell and Duryodhana in heaven as an illusion. It was a punishment for his lie in the Kurukshetra war about the death of Ashwathama, that lead to the killing of preceptor Drona. Later he saw his brothers in heaven. He also saw Duryodhana in heaven, and he was informed that he will be in heaven for a short period to enjoy the fruits of his good deeds like rescuing Karna from humiliation when he was insulted on behalf of his caste. It is very clear that Swargarohana Parva is an addition to Mahabharata. It was added to record the beliefs in heaven and hell, that became popular in ancient India, long after the age during which the war of Kurukshetra occurred.