I don't know what a previous poster meant by mentioning Augustine and Aqunas and then saying "the morality developed during that period" (Augustine 4th century BC, Aquinas 13th century). The truth is that Augustine was especially heavily influenced by Plato and Aquinas' entire philosophy was mostly an attempt to synthesize Aristotle with Christianity. There is a tendency by some Christians to think morality somehow can't exist without God, but the truth is otherwise. The Greeks certainly had well-developed modern morality, along with brilliant moral theory. And the reality is that most of the important advancements in morality have come from "liberal", often secular, thinkers, while Christianity (and other religions) get pulled upward from old barbarisms only while kicking and screaming.
Any references for this? I find it highly doubtful.
The Greek philosophy was universal in that it applied to anyone who was a "person". I don't think that's different from any morality that's followed, it's just that the "universe" has always been limited, e.g., in U.S. rights were created universally for "all men", but that didn't originally include women or slaves.
Pretty much every philosopher is influenced by the great philosophers who came before them. If you look at philosophical (or indeed scientific) work today, it is no less under the influence of previous work. Augustine and Aquinas were very original in many respects, but they quite rightly built on the best philosophical ideas that they knew of rather than starting from scratch just for the sake of it.
He died in 430 AD, 20 years after the sack of Rome by Visigoths. Pretty much what people call the beginning of medieval period.