The following is from a work-in-progress called The Mahabharata: a Book Report, in which I'm slowly reading through the Hindu epic poem The Mahabharata, and writing a book report on what I read.
Both the Kauravas and the Pandavas were taught martial arts by a master named Drona. The best of the warrior-princes was Arjuna. After the princes finished their training, Drona arranged a tournament to demonstrate his pupils' skills. The first match was between Duryodhana (eldest of the Kauravas) and Bhima (strongest of the Pandavas). However, before they could fight, the crowd became so divided and unruly that Drona called off the match, fearing a riot.
To satisfy the unruly audience, Arjuna gave a demonstration of his amazing skills, particularly as an archer. As the prince was wowing the crowd with his impressive bowmanship, he was interrupted by the sound of an arm beating against a chest. Who should appear, but Karna, half-brother of Arjuna, son of the Sun god and Kunti! Karna was a large and impressive warrior, and he challenged Arjuna to a fight, saying, "Son of Kunti, whatever you have done, I shall outdo it before the eyes of all these men!" Sensing an opportunity, the wicked Duryodhana forged an alliance with Karna. Then the two great heroes prepared to duke it out.
As they prepared to fight, there was a corresponding conflict in the heavens. Indra, the god who'd partially incarnated himself in Arjuna, created lighting, thunder, and rainbows. The sun god, who'd partially incarnated himself in Karna, burned away the clouds of Indra. And so, in this earthy conflict between Arjuna and Karna, there was a corresponding conflict in the sky between Indra and the sun god.
Meanwhile, Kunti, the mother of both warriors, fainted and was revived by Vidura the wise. This was a lose-lose situation for her. Kunti "gazed at her two sons in their armor, and she grieved."
At this point, a guy named Krpa announced that, before fighting the prince Arjuna, Karna must prove that he is royalty. Because he was unable to do so, Duryodhana intervened and proclaimed Karna king of a region called Anga. In gratitude, Karna pledged his loyalty to Duryodhana forever. Bad choice, Karna. Then Karna's earthly father showed up, basically demonstrating that Karna was not, in fact royalty. Bhima thought this was hilarious, and proceeded to insult Karna. Duryodhana argued that the true source of kingship was not in birth--a fairly radical idea.
Basically, the tournament never really happened. Everyone got into an argument about the qualities of kingship, and then the sun went down and everyone went home. Meanwhile, the kingdom of Hastinapura was increasingly divided between the supporters of the Pandavas and the supporters of the Kauravas. A conflict was brewing.