The Knights Templar came into being sometime around 1100. Employed by the Pope, they were headquartered in the Temple Mount in Jerusalem - a city that had recently come under Christian control in 1099, thanks to the First Crusade (led by the Franks).

The newly conquered Holy Land attracted pilgrims, and the knights were tasked with protecting believers on what could be a perilous journey. The Knights Templar are largely responsible for our modern image of knights as virtuous heroes - before the Knights Templar, the best-known knights would have been little more than privileged local nobles and warlike bullies.

More Info: en.wikipedia.org