The Iksar Monks actually owe their existence to a very famous Human monk, one of the first of his kind who in his hubris attacked Cazic Thule on his home Plane of Fear. The story is related as part of the quest for the Whistling Fists via an in-game book given by Cazic Thule himself:
Zan Fi believed in his power and made way to do battle with Cazic Thule in his own plane. Dispatching his minions one by one he came to the Lord of Fear. He saw and threw challenge to him. The battle lasted for days, Cazic Thule was weakened but Zan Fi would be defeated in the end. Cazic Thule seeing this amazing skill in battle decided that it should be instilled into the broodlings of his great race. He took the essence of Zan Fi and placed it into an Iksar, Tynn. Cazic Thule bestowed unto Tynn the gift of the Whistling Fists. He did this as a mockery of Zan Fi and his failure in battle. He was placed within the empire of Iksar with only one thing in mind, to train other Iksar the way of the monk to inflict a new breed of fear and pain unto their foes.
After his creation Tynn proceeded directly to fulfilling his god's bidding and his story is related in an in-game book:
It was in dawning of the Sebilisian Empire that the art of fist and tail was forged. In the begining the pugilists of the great tribes were nothing more then warriors without weapons. Soon we would be forged into weapons.
Grandmaster Tynn was the father of our disciplines. He came to the empire from an unknown tribe. Some say he was a ronin who wandered the worlds of Norrath were he formed the basis of our discipline. He entered the city of Sebilis with no rebirth. He entered to form a caste which did not exist.
He was quickly challenged by the warlords. He spoke his words and they did not listen. He knew the only way to make them understand was to challenge their finest in The Gauntlet. He called for four of the finest warlords and allowed them arms. The warlords agreed thinking his challenge an easy task.
Grandmaster Tynn quickly dispatched of the warlords with nothing more then fist and tail. He fought in a way never displayed. His victory earned him much respect and Emperor Sathir soon commanded him to form the Court of Pain and raise an army of monks. Tynn formed the Swifttail Caste.
Soon the way of the fist and tail had hundreds in it's ranks, climbing the rungs. Tynn showed them they were not warriors, but monks. They would don shackles as testament to the Age of Snake when the Iksar were a race enslaved. Inner strength and harmony were taught. The Swifttail were born.
The Swifttail were disbanded during the End Days. It was not till the rise of the new empire under Emperor Vekin did the caste reform. Grandmaster Glox, a former disciple of Tynn, came to New Sebilis to rebuild the Court of Pain. In honor of Tynn, all masters now drape themselves in a robe like he wore.
This is why the pipe of Zan Fi appears as a requirement of the robe of the Lost Circle quest, the final Iksar Monk Shackle is called "The Shackle of Tynn" and the bones of Zan Fi can be found in the Feerot by a gnome unsuccessfully attempting to resurrect them (they were discarded after being used by Cazic and thown back out the portal to his Plane of Fear in the Feerot).