Short answers, pulled from the story.
Mycenaean Greek is the earliest known dialect of the language. It appears on Linear B tablets from the late 2nd millennium BC within Bronze Age civilization that dominated mainland Greece before its collapse.
Aeolic spread across Lesbos, Asia Minor north of Smyrna, Boeotia, and Thessalia while Doric expanded toward the Peloponnesus coast including Sparta Crete and southernmost areas of the west coast of Asia Minor. Northwest Greek sometimes stands as a separate entity or falls under the broader Doric classification.
Heraclitus Hecataeus Herodotus Democritus and Hippocrates all wrote philosophical or historical works in Ionic. Plato Aristotle and Thucydides wrote philosophy in Attic while Attic orators like Lysias Isocrates Aeschines and Demosthenes used their native dialect for public speeches.
Vowel contractions distinguished regional speech forms through specific sound changes such as loss of intervocalic s consonantal i and w bringing two vowels together creating hiatus situations. Ionic changed resulting *a to an e producing poseideōn while Attic contracted it to poseidōn and Doric retained original ā forms throughout their histories.
Mycenaean was deciphered only in 1952 so it appeared absent from earlier classification schemes entirely. No other classical dialect possesses a direct predecessor from this Bronze Age era yet the relationship between these later forms and their Mycenaean ancestors remains unknown to modern scholars.