In ancient Roman religion, the Arval Brethren (Latin: Fratres Arvales, "Brothers of the Fields") or Arval Brothers were a body of priests who offered annual sacrifices to the Lares and gods to guarantee good harvests.Inscriptions provide evidence of their oaths, rituals and sacrifices.
Roman legend held that the priestly college was originated by Romulus, first king of Rome, who took the place of a dead son of his nurse Acca Laurentia, and formed the priesthood with the remaining eleven sons. They were also connected originally with the Sabine priesthood of Sodales Titii who were probably originally their counterpart among the Sabines. Thus it can be inferred that they existed before the founding of the city. There is further proof of the high antiquity of the college in the verbal forms of the song with which, down to late times, a part of the ceremonies was accompanied, and which is still preserved. They persisted to the imperial period.
Arval Brethren formed a college of twelve priests, although archaeologists have found only up to nine names at a time in the inscriptions. They were appointed for life and did not lose their status even in exile. According to Pliny the Elder, their sign was a white band with the chaplet of sheaves of grain (Naturalis Historia 18.2).
The Brethren assembled in the Regia. Their task was the worship of Dea Dia, an old fertility goddess, possibly an aspect of Maia or Ceres. On the three days of her May festival, they offered sacrifices and chanted secretly inside the temple of the goddess at her lucus the Carmen Arvale. The magister (master) of the college selected the exact three days of the celebration by an unknown method.