Earliest known Latium was the country of the Latini, a tribe whose recognized center was a large, extinct volcano, Mons Albanus ("the Alban Mount", today's Colli Albani), 20km to the southeast of Rome, 64km in circumference.
The selection of Jupiter as a state god and the descent of the name Latini to the name of the Latin language are sufficient to identify the Latins as a tribe of Indo-European descent.