For 10 points, name this domain occupied by the Roman god Sol.
Herodian related how one monarch worshipped a god of this domain by walking backwards while holding the reins of an unmanned chariot during a festival. Vespasian converted Nero's massive statue to one of a god of this domain. One god of this domain was represented by a black stone taken from Emesa. A common scene in Mithraic iconography shows Mithras dining with a (*) god of this domain atop a slaughtered bull. Marcus Aurelius Antoninus came to be known as Elagabalus due to his propitiation of a god of this domain imported from Syria. Saturnalia and a feast dedicated to a god of this domain were absorbed into Christmas in the 4th century. Aurelian propagated a cult of a god of this domain known as the "unconquered," or Invictus. For 10 points, name this domain occupied by the Roman god Sol.
Herodian related how one monarch worshipped a god of this domain by walking backwards while holding the reins of an unmanned chariot during a festival.
sun [or Sol Invictus before “Sol” is mentioned; or Sol Indiges before “Sol”; accept Elagabal or Elagabalus or Heliogabalus before “Vespasian”]