A good article on the ancient sport of pankration:
"Eventually, Pankration became the core focus of a Greek soldier’s hand-to-hand training regime. This evidence suggests that Pankration was created to supplement a warrior’s battle prowess (as weapons would often break and combatants would have to use their bare hands and feet).
Ancient literary sources state that wrestling was a very important component of a Greek hoplite’s repertoire (heavy infantrymen were called hoplites). Hoplites would use their wrestling skills to stay balanced and get back to their feet quicker than the enemy if they fell down. Getting back to your feet quicker was often the difference between life and death.
Over time, the accomplishments of the strongest and most successful Pankratiasts formed the basis of legendary stories and mythical embellishments. One famous tale focuses on the Olympic victor Polydamas, who was rumored to have killed three fully armed Immortals (elite Persian warriors) with only a stick, after the king Darius invited Polydamas to his court and had him ambushed to test his skills.
Some competitors were well-rounded enough to win both the boxing/Pankration and wrestling/Pankration events at the same tournament, with the latter feat occuring more often than the former. The available evidence suggests that grappling was more integral than striking and that most fights ended on the ground, so those better trained in wrestling and submissions had an advantage in Pankration fights.
Rules and Regulations
There were two kinds of Pankration: ano pankration (when the fight had to stay standing, similar to kickboxing) and kato pankration(in which the fight could go to the ground). Only two rules prevailed: no biting and no eye gouging (similar to the early UFC events). In Sparta, even these techniques were allowed during their bouts.
Pankratiasts would compete naked in a wrestling-pit, and the referee would use a rod to enforce the rules. There were no rounds or time limits, and the fight only ended once somebody gave up or was rendered unconscious (or dead). Fighters would signal defeat by raising their arm or tapping out.
Fatalities were common, especially by strangulation, as many fighters refused to give up after being caught in a choke. Submissions were prominent, and there is ample evidence to suggest that the ancient Greeks knew all or almost all the submissions that current fighters use today, including knee bars, heel hooks, and a variety of chokes and arm locks.
Kicking was not neglected either, and one source sarcastically states that the prize in Pankration was awarded to a donkey due to his kicking ability. Broken fingers were often sustained while trying to sink in a submission, and even broken necks. An age group for younger competitors was introduced around 200 BC.
Pankration was regarded as dangerous, bloody, and brutal even by the ancient Greeks, who were certainly no strangers to the art of war and violence. Pankratiasts fought for honor and pre-eminence amongst their peers, and were very proud warriors. They would often rather die than submit to an opponent." - More