 By the 9th century, there was an active rivalry between these scholar-priests and ritual priests, with each group underbidding the other in their attempts to secure an income.For Zoroastrian laypersons, the distinction between the two groups was at best theoretical and by the 10th century, the term "hērbad" had lost most associations of scholarship and eventually came to refer to priests that had no theological authority.Beyond that distinction, the terms "hērbad", "mobad" and "dastūr" were used interchangeably.