Eastern Thrace (Doğu Trakya in Turkish, although almost always called simply Trakya, i.e. Thrace) is European Turkey, i.e. part of Turkey that is located in Europe. It forms northwestern edge of the country. Note that this region is only European geographically and not culturally. The majority religion is Islam and the region draws influence from mainland (Asian) Turkey through mosques and lifestyle, but above all, the hallmarks of European civilization and culture such as those associated with the Age of Discovery are not found in European Turkey.
Geographically, western half of Istanbul Province is also part of Eastern Thrace.
Istranca Mountains and Black Sea coast
Lush mountains, lakes, and desolate beaches
Marmara and Aegean coasts
Miles of beaches, stony and sandy, crowded and lonely alike; fishing towns, vineyards, and pine forests here and there
Geographically speaking, the city of Istanbul is also partially in Eastern Thrace, but culturally it is a world afar and should be considered as a region on its own.
Eastern Thrace is located in the northwestern corner of Turkey and makes up 3% of the country’s landmass. Although this percentage might seem small at first, Eastern Thrace is only slightly smaller than whole of Belgium, for example.
Eastern Thrace is essentially a peninsula surrounded by Greece (Western Thrace) and Bulgaria (Northern Thrace) to the west and north respectively and bouded by Black Sea, Bosphorus, the Sea of Marmara, Dardanelles, and the Aegean Sea to the northeast, east, south, and southwest respectively.
Central parts of Eastern Thrace are dominated by Thracian plains, which are fairly...well, plain. These plains produce much of the country's wheat and sunflower, and a ride through in sunflower season (July) is indeed very pleasant amongst yellow flowers. However, being one of the powerhouses of Turkish economy, more east you go on the plains, less agricultural the landscape becomes—around Çerkezköy and north, west, and east of Çorlu is essentially nothing other than urban conglomeration going hand in hand with endless rows of factories. Northeastern coast and its adjacent area, on the other hand, is dominated by low-lying range of Istranca Mountains covered with lush broadleaf forests, typical of Turkish Black Sea coast, as well as the northern reaches of the region along the Bulgarian border. Southwestern parts dominated by Ganos and Koru Mountains, another low lying mountain range, and Gallipoli Peninsula are covered mostly with pine forests, in addition to vast vineyards on the foothils of Ganos Mountain, which supply almost half of Turkey's wine production.
Culture of today’s Eastern Thrace shares many similarities with cultures of Balkan (Southeastern Europe) countries as much of the region’s population is descendants of people who immigrated from those countries starting from late 1800s to the date.
Eastern Thrace is a part of Marmara Region.
Thracians, an ancient people speaking an Indo-European language and whom the larger area surrounding the region was named after (which derived from the Thracian Zrayka) were the native folk of the region. Except a brief period during Odrysian Kingdom (5th–3rd century BC), these warrior tribes never formed a united nation. Except for landmark-ish tumulii, which they erected for their nobles as monumental tombs, not much other than some ruins and artifacts hardly distinguishable from natural formations by untrained eyes is left physically from this period, although some villages and rivers across the region still carry names that are phonetically corrupted forms of their original Thracian names.
Around 4000 BC, Greek colonists from Aegean Islands made their debut in the region along the Marmara coast, although never succeed to penetrate much inland due to opposition of vicious Thracian tribes. Some of the cities Greeks founded in the region still exist to this day, such as Tekirdağ.
Around 335 BC, Alexander the Great—part of army of whom was actually consisted of Thracian troops—showed up in the region on his way to India.
It was the Romans—who took over the region around the early years of Christ—who first truly united the region into a single authority and named it the province of Thracia. Since the region was on the main route (named Via Egnatia) between the later Roman capital of Constantinople and Rome, the other major city of the empire, it never fell into a backwater status.
After the Roman Empire was divided in two, Eastern Thrace consecutively changed hands between Bulgarian Kingdom and Byzantine Empire, or Eastern Roman Empire, several times in 10th century CE.
Ottoman Turks set foot in around 1350s for the first time in Thrace (and in Europe). Eastern Thrace was mainly the warehouse and breadbasket of the imperial capital of Constantinople during this period in addition to its strategic importance stemmed from the fact that it lies on the major routes between the capital and its European possessions.
During the turmoil before, during, and after WWI, local Greeks and Bulgarians, who formed a substantial part of region's population, emigrated to Greece and Bulgaria respectively, and replaced in return by Turkish/Muslim immigrants from mostly Greece and Bulgaria, but also from other Balkan countries. 1950s also saw a Jewish emigration from the region towards newly-founded Israel.
While being not a very large region, Eastern Thrace has a variety of different climate types that lie close to but are substantially different from each other. Inland areas have temperate continental climate that is similar to that found in inland regions of Balkans, while milder climate of places on the Black Sea coast resembles more of an oceanic climate, typical to other areas of Turkish Black Sea coast. Climate of areas on Marmara and Aegean coasts is similar to the Mediterranean climate, though strong winds carry continental influences easily down to coast, making it much colder than it might be, considering its fairly southern latitude.
In general, no matter where you are heading in the region, consider these facts when planning your trip:
Turkish is the language of choice in the region, as elsewhere in Turkey. The local dialect is loaded with slang and other colloquially used words mainly originating from other Balkan languages (mainly Bulgarian), but this won’t be a problem if you can speak Turkish as local folk mostly avoids using them (or “translates” them into standard Turkish) when they see you’re non-local. Also, the local dialect is one of the most similar dialects to standard Turkish (which is based on Istanbul dialect).
The most frequent foreign language is English. Thousands of immigrants from Bulgaria, who were settled in the region in late 1980s/early 1990s, means that finding someone who speaks fluent Bulgarian is also a possibility (albeit a minor possibility).
There are four border posts with Bulgaria (one rail, others highway) and three border posts with Greece (one rail, others highway), most of which are located on the banks of Maritsa River (Turkish: Meriç, Greek: Evros), which forms most of the Greco-Turkish border. The major ones are Dereköy north of Kırklareli (highway crossing into the Bulgarian Black Sea Coast), Kapıkule west of Edirne (known as Kapitan Andreevo on the other side of the border, highway crossing into Central Bulgaria, which can have quite long queues in summer), Uzunköprü (railway crossing into northeastern Greece) and İpsala west of Keşan (highway crossing into northeastern Greece). There are trains  and buses crossing any of these border posts.
The region is also well connected to Istanbul by highways and a motorway (toll-road), buses and trains. It’s even possible to find a direct bus from Istanbul to a village well off-the-beaten-path. Please note that all trains to the region departs at European station (Sirkeci) of Istanbul, not Haydarpasa, the Asian one
There is also a substantial number of ferries connecting towns and cities located on the southern and northern (Thracian) coasts of the Sea of Marmara.
All cities in the region are connected to each other by bus, and smaller towns have minibus connections to nearby bigger towns and cities.
There are also many (relatively) long-haul inter-town dolmuş lines in the region started recently, such as between Keşan and Çerkezköy via Tekirdağ and Çorlu or between Gelibolu and Silivri, via Tekirdağ and Marmara Ereğlisi. These are faster and slightly more expensive than buses.
The only line out of Istanbul’s European station (Sirkeci) splits into two near Babaeski, one of them continues towards Bulgaria and the other one towards Greece, there is at least one daily train (both local and international) operating in each line. As the railline wasn’t laid down as straight as the highways, train journeys take more time than bus/car travel.
The main highways of the region radiate out of Istanbul and generally follow a straight line towards Greek and Bulgarian borders, and Aegean Sea. Here is a list of the road numbers of main highways of the region and the notable towns and cities located along:
All roads in the region, even those leading to far away villages, are sealed, although pavement quality and road breadth varies according to how important and busy the road is.
The major crossroad with traffic lights near Keşan is probably number one hitchhiker’s paradise in the region as there are major roads leading to all cardinal directions there, and all vehicles have to stop (or at least slow down) because of traffic lights. And there are lots of vehicles, day or night. And as a bonus, there is a huge supermarket nearby to replenish the supplies. It’s even possible to get a lift all the way to Ukraine or Italy or Iran there (judging from the plate numbers of the trucks).
Tekirdağ and Uzunköprü in the region are known for their local meat-balls (köfte), while Edirne is known for its fried liver (ciğer). The region, surrounded by three seas and fragmented by riverbeds, also offers many different kinds of fish.
This region provides much of Turkey’s wine and raki production and a considerable percentage of beer production. Don’t forget to check out local brands (although most of them are available almost everywhere in Turkey –except wine).
Drivers should be aware that all place names on highway signs are written in Turkish, as elsewhere in Turkey. These include the place names out of Turkey, too, no matter how different their Turkish names are from their native or English counterparts. Some such as Burgaz or Sofya are close enough to their native/English spellings, as if there just have been a spelling error on the sign, but what is Yunanistan? And which direction on Earth is Greece? Don’t get your eyes weary by looking for ‘Greece’ or ‘Bulgaria’ on the signs, here is a short list of what you should look for instead (and what you will see commonly on the roads towards the border) (Turkish names written in italics, English names in paranthesis): Yunanistan (Greece), Batı Trakya (Western Thrace), Gümülcine (Komotini), Dedeağaç (Alexandroupolis), Selanik (Thessaloniki), Bulgaristan (Bulgaria), Burgaz (Burgas), Sofya (Sofia)… And hudut, which you will see frequently on signs counting down the distance as well as on the directional signs, means ‘border’. One hint: All place names out of Turkey, as well as the names of the border posts, are written over a yellow or brown band on otherwise normally blue or green highway signs (but keep in mind that the same yellow or brown signs are also used for places of historical and/or touristical interest, too).