Short and long occurred in pre-Modern Greek. In the Attic and Ionic dialects of Ancient Greek, front developed by fronting from back around the 6th to 7th century BC. A little later, the diphthong when not before another vowel monophthongized and merged with long . In Koine Greek, the diphthong changed to , likely through the intermediate stages and . Through vowel shortening in Koine Greek, long merged with short . Later, unrounded to , yielding the pronunciation of Modern Greek. For more information, see the articles on Ancient Greek and Koine Greek phonology.