In the ancient ages, Alaçatı was called “Agrilia”. It was situated in the center of a region called “Ionia” in the Western Anatolian history, which extends from south of Izmir to the Menderes River. The closest “Ionic” city to our town was called “Erythrai” which is a village of Alaçatı now known as “Ildiri”, which is followed by “Chios” and “Klazomenai” now called Sakız adası and Urla iskelesi respectively.The name of Alaçatı came across in the sources as “The Itineraries of Evliya Çelebi” for the very first time during the early Ottoman era. The town has taken its name “Alacaat” from an Alacaat tribe that had settled in the village. In the 1830s, the story of this peaceful town started to changing for the better when one of the region’s prominent persons, Haji Memis Agha, - a name still living as one of Alaçatı’s neighborhoods today - invited the impoverished Greek people of Chios, that was shaken by earthquakes in those years, to the town to work in various jobs. While local people were fighting in wars, the Greek youngsters started working in the vineyards and olive farms.
The Alacaat people were also fighting against malaria because the southern part of the village was covered with swamps.To drain the swamps, they decided to open a channel to the port of Alaçatı. For this reason, the large Turkish landowners provided shelters in their lands for the Greek workers who were going to work in the canal construction in order to enrich their fields as well. So, the workers set up a new village a few miles inland from the sea. The stone houses renovated today were mostly built between 1850 and 1890. In the end of the 19th century “Alatzata” village, as Greek people called it, has become an important production and trading city famous for its vineyards and grapes. Majority being Greek, the population reached 12.000. While the migrants fleeing Balkans in the Balkan War of 1912 started to settle in Alaçatı, Greeks started to leave. Turkey and Greece signed the “population exchange” treaty in 1923 and about 2 million people were moved from their homes. According to the treaty, Moslems living in Greece, except Orthodox Greeks in Istanbul and Moslems of the Western Thrace, were shipped to Turkey and Orthodox Greeks living in Turkey were sent to Greece. So, the population of Alaçatı completely changed within 10 short years as the exchanged population from Thessaloniki, Kavala, Crete and Istankoy (Cos) were added to the Albanian and Bosnian immigrants coming from Kosovo and Bosnia during the Balkan War.