In the first decades of the twentieth century the geographical framework of the whole Balkan peninsula was transformed and new developments affected, directly or indirectly, the life of its inhabitants.

Military confrontations resulted in waves of refugees, deportations, settlements and resettlements: large population groups were put into motion. In the period following the Balkan Wars and later, in the course of the First World War, clashes and the intense hostility between the Balkan states brought the problems inherent in the presence of populations of different nationality. Large population groups followed the retreat or advance of troops. At the same time, the Balkan governments exploited the presence of foreign populations in their national territory in order to exert pressure on their opponents.

These conditions led to the arrival in Greece of a large number of Greek refugees originating from various Balkan countries. These refugees came from Bulgaria, Western Thrace (under Bulrgarian control at the time) and areas of Macedonia beyond the Greek frontiers. They also originated from Asia Minor and Eastern Thrace, where the Young Turks had inaugurated the systematic persecution of Greeks with the result that many of them fled to Greece, whereas others were deported to the interior of Asia Minor.

The annexation of the largest part of Macedonia to Greece beyond its essential economic and political implications meant the integration of new landless farmers, frequently of different national-cultural origins, in the productive potential of the country. Thus, in the 1910s, a large number of Bulgarian and Turkish Muslims residing in the New Territories departed for Bulgaria and Turkey.

It must also be added that during the course of the First World War, part of Macedonia became a battlefield, a fact that contributed to the movement of populations. Also, in 1919 refugees reached Greece from the Soviet Pontus, in an organized expedition undertaken by the Greek state for their evacuation and transfer to Greece. Most of them settled in the territories of Macedonia.

Towards the end of 1914 there were 150,000 refugees in Macedonia while the number in southern Greece has not been defined. The total number of refugees asking for the aid of relief services reached that period 117,484. Some effort was made to provide them relief, not an easy task under the prevailing conditions. In the field of housing results were poor due to the lack of materials and resources. The government tried to resettle them on public agricultural lands, because large estate owners would not hire them as farm labourers. Their absorption as industrial workers in the cities was equally difficult. Until 1915 the overall expenses of the state regarding the resettlement of refugees reached 15,817,640 drachmas. An inability to support them was one of the factors that had contributed to the decision for agricultural reforms in 1917.

After the end of the First World War a large proportion of the Greek refugees of that period returned to their places of origin. Those originating from western Thrace settled permanently in their homelands, while many Asia Minor inhabitants and the inhabitants of eastern Thrace returned to their homeland during the Greek occupation, until the Catastrophe of 1922 and the exchange of populations.