Complex sentence: The Roman temple architecture style was derived from the Etruscan model, an indigenous Italian race which was at its peak in the seventh century BC. In turn, the Etruscans had adopted other styles into their temples, of which Greek architecture was the main influence.
Split into simpler sentences: The Roman temple architecture style was derived from the Etruscan model. The Etruscans were an indigenous Italian race which was at its peak in the seventh century BC. In turn, the Etruscans had adopted other styles into their temples, of which Greek architecture was the main influence.