The Pandavas were the five sons of the king Pandu. They are among the main protagonists of the Mahabharata. Pandu inherited his father's kingdom, despite being the younger of the two brothers, because his elder brother Dhritarashtra was born blind.
Pandu took two wives: Kunti and Madri. Kunti, originally named Pritha, was the sister of Vasudeva who was the father of Krishna. She was informally adopted by her paternal uncle Kuntibhoja, whereupon she was renamed Kunti. Madri was a princess of the Matsya kingdom.
Pandu accidentally killed a deer who was in the very act of copulation. The deer, who was actually a rishi, laid a curse upon Pandu to the effect that he, Pandu, would fall dead should he ever again approach a woman. This curse caused Pandu to retire to the forest with his two wives, there to lead a chaste life, leaving the kingdom to the blind Drithrashtra.
In her younger days, Kunti had been taught a powerful mantra or invocation by the rishi Durvasa. By using that mantra, she could summon any deity of her choice, who would beget a son by her. Pandu asked Kunti to use this boon so that she need not remain childless due to the curse on him. Kunti invoked in turn Yama Dharma Raj, the god of justice and death; Vayu, (the god of wind); and Indra, (the king of the gods) and gave birth to Yudhisthira, Bhima and Arjun respectively by them. She also imparted the mantra to Madri, who invoked the Ashwini twins and give birth to the twins Nakula and Sahadeva.