The Coptic New Year is the very first calendar ever known by man, going back as far as 4241 BC.
The word "Nayrouz" is of Coptic origin. The stem is niiaro-oo meaning: "the rivers". The suffex "ouz" is Greek, thus, the word "Niiaroouz."
Mid-September is usually where the waters of the Nile river rises, so the prayers are lifted to God for the rising of the waters of the rivers for irrigation and ask for His blessings at the beginning (crown) of the Coptic Calendar year.
When the Persian ruled Egypt from 525-405 BC, they adopted the word and incorporated it in their language and took it to mean "the beginning of their Persian year," and called it "Nayrouz". The word "Nayrouz" in Persian, means "the new year."