Turkey became one of the main launch points for more than a million migrants taking the sea route to EU territory in 2015, many fleeing conflict and poverty in the Middle East and Africa.
The effects of the war in Syria have been felt far and wide, especially in Europe which has witnessed a huge influx of refugees.
In 2015, over a million reached the continent, with Germany taking the most.
The influx of migrants was drastically curtailed by a 2016 accord between Ankara and the EU, after hundreds died crossing to Greek islands a few miles off the Turkish shore.
A summit between the leaders of Turkey, France, Germany and Russia will be held in Istanbul on Saturday to discuss the conflict in Syria and efforts for a lasting solution to the war in the country.
TRT World's Simon McGregor-Wood takes a look back at the Europe's refugee crisis.