Dodecanese relative quiet and prosperity. In 408 BC, the three cities of Rhodes had united to form one state, which built a new capital on the northern end of the island, also named "Rhodes"; this united Rhodes was to dominate the region for the coming millennia. Other islands in the Dodecanese also developed into significant economic and cultural centers; most notably, Kos served as the site of the school of medicine founded by Hippocrates. However, the Peloponnesian War had so weakened the entire Greek civilization's military strength that it lay open to invasion. In 357 BC, the islands were conquered by
Koine Greek dialects and its own "Koine" form, which have preserved some of the ancient language's oral linguistic details which the written tradition has lost. For example, Pontic and Cappadocian Greek preserved the ancient pronunciation of etc.), while the Tsakonian language preserved the long α instead of η ( etc.) and the other local characteristics of Doric Greek. Dialects from the southern part of the Greek-speaking regions (Dodecanese, Cyprus, etc.), preserve the pronunciation of the double similar consonants (), while others pronounce in many words υ as ου or preserve ancient double forms ( etc.). Linguistic phenomena like the above imply that