History of the Greek alphabet retained the sound. A symbol based on the left-hand half ( ├ ) of the letter Η was therefore sometimes used to indicate the presence of where necessary, and its absence was indicated by a symbol based on the right half. During the classical period, ΕΙ came to be pronounced and ΟΥ came to be pronounced , Υ having meanwhile moved to . By about 200 BC, a system of diacritical marks was invented, representing the tone accents in use in Ancient Greek. This also helped to indicate the length of the vowels Α, Ι, and Υ in certain cases
History of the alphabet Asia Minor (also called Asian Greece i.e. present-day aegean Turkey). The Athenians (c. 400 BCE) adopted that latter variation and eventually the rest of the Greek-speaking world followed. After first writing right to left, the Greeks eventually chose to write from left to right, unlike the Phoenicians who wrote from right to left. Many Greek letters are similar to Phoenician, except the letter direction is reversed or changed, which can be the result of historical changes from right-to-left writing to boustrophedon to left-to-right writing. Greek is in turn the source of all the modern scripts of Europe. The alphabet of