Zhengyi is the liturgical tradition of Taoism, and its priests are not monks. They marry, live in the communities they serve, work at other trades, and pass their office, their registers and their manuscripts within the family. Where Quanzhen produced monasteries, Zhengyi produced a hereditary profession.
The lineage claims descent from Zhang Daoling, who by tradition received a revelation from Laozi in the year 142 and founded the movement called the Way of the Celestial Masters, which built an effectively autonomous religious polity in Sichuan by the end of the second century. That is the tradition's account of its beginning, and the date is a traditional one. The Zhengyi name as an umbrella is much later: in 1304 the Yuan court placed all Taoist schools other than Quanzhen under it.
The priest's work is ritual performed on behalf of a community. He conducts liturgies addressed to the gods and to ancestors, draws and empowers talismans, performs rites of healing, blessing and exorcism, and presides at the jiao, the great offering that renews a community's relationship with its gods and may run for days.
His authority rests on a register conferred at ordination, naming the spirits he is entitled to command. The model is bureaucratic, and deliberately so: Taoist ritual addresses the celestial administration in the forms of a memorial submitted to a government office, because that is precisely what it takes itself to be doing. The heavens are staffed, and the paperwork must be correct.