important member of West Greek, originated from western Greece. Through the Dorian invasion, Doric displaced the native Arcadocypriot and Aeolic dialects in some areas of central Greece, on the Peloponnese, and on Crete, and strongly influenced the Thessalian and Boeotian dialects of Aeolic. Doric dialects are classified by which vowel they have as the result of compensatory lengthening and contraction: those that have are called Severer or Old, and those that have , as Attic does, are called Milder or New. Laconian and Cretan, spoken in Laconia, the region of Sparta, and on Crete, are two Old Doric dialects. Attic and Ionic Attic and Ionic share a vowel shift not present in any other East or West Greek dialects. They both raised Proto-Greek long to (see below). Later on, Attic lowered found immediately after back to , differentiating itself from Ionic. All other East and West Greek dialects retain original . Ionic was spoken around the Aegean Sea, including in Ionia, a region of Anatolia south of Aeolis, for which it was named. Ionic contracts vowels less often than Attic (see below). Attic is usually the dialect taught in modern introductory Ancient Greek courses, and the one that has much of the most important literature written in it. It was spoken in Athens and Attica, the surrounding region. Old Attic, which was used by the historian Thucydides and the tragedians, replaced the native Attic with the of other dialects. Later writers, such as Plato, use the native Attic forms. Later Greek Koine, the form of Greek spoken during the Hellenistic period, was primarily based on Attic Greek, with some influences from other dialects. It underwent many sound changes, including development of aspirated and voiced stops into fricatives and the shifting of many vowels and diphthongs to (iotacism). In the Byzantine period it developed into Medieval Greek, which later became standard Modern Greek or Demotic. Tsakonian, a modern form of Greek mutually unintelligible with Standard Modern Greek, derived from the Laconian variety of Doric, and is therefore the only surviving descendant of a non-Attic dialect. Consonants Attic Greek had about 15 consonant phonemes: nine stop consonants, two fricatives, and four or six sonorants. Modern Greek has about the same number of consonants. The main difference between the two is that Modern Greek has voiced and voiceless fricatives that developed from Ancient Greek voiced and aspirated stops. In the table below, the