The Roman Senate kept tight control over the Sibylline Books; "Sibylline Books" were entrusted to the care of two patricians; after 367 BC ten custodians were appointed, five patricians and five plebeians, who were called the "decemviri sacris faciundis"; subsequently (probably in the time of Sulla) their number was increased to fifteen, the "quindecimviri sacris faciundis".