Adi Shankaracharya was born in the 8th Century AD. He is recognized to be the undisputed spiritual leader of India, and propagated the Advaita Vedanta philosophy which leads directly to the experience of higher yogic life.
During the course of his life, he established the Dashnami Sannyasa tradition in order to unify the various and diverse groups of sannyasins which were scattered throughout the country, bringing them all under the banner of sanatana dharma.
Dashnami Sannyasins still continue to convey his eternal message of the synthesis of all beliefs culminating in Advaita, the monistic vision of reality in which all things are understood, ultimately, to be one.
(Ref: www.biharyoga.net)