Polykastro (Greek: Πολύκαστρο, before 1928 Καρασούλι, Karasoúli;[2]) is a town and a former municipality in Kilkis regional unit of Central Macedonia, Greece.

In Byzantine times there were many wars with the northern tribes, as Avars, Vardars, Bulgars and Slavs and the area was severely affected.

In the 13th century, the Byzantine Emperors rebuilt the fortress of Vairos in order to face the northern enemies.

[7][9] It is remarkable that in the villages Evzoni and Korona, people used to speak a Romance dialect, called Megleno-Romanian.

Researcher Maria Papageorgiou claims that a lot of plays of ancient Greek tragic poets, not preserved nowadays, were kept verbally, in this dialect, as tales.

During the Greek War of Independence, people of Polykastro fought against the Ottomans in the revolutionary movement of Bogdanci, but were unsuccessful.

Two Greek churches and one school were built in the village, they are known as Agii Anargyri (Taxiarches nowadays) and Agios Athanassios.

In the nearby village of Vogoroitsa (now Bogorodica, in the Rep. of North Macedonia) act troops with leaders: Christos Dringas and Dimitrios Ouroumis.

[16] The ethnic composition of the village according to Vasil Kanchov in 1900 was 340 Bulgarians, 200 Turks, 12 Adyghe and 55 Romani people.

[7] According to these sources them the population of the area of Polykastro municipality was 7,000 people, 1,000 of whom Greeks, 4,000 Bulgarians and 2,000 Muslims, mainly Turks.

The Greek commander Georgios Karaiskakis from Bogdanca (now in the Republic of North Macedonia) and his troop were the main defenders of the area.

Georgios Karaiskakis"Vogdantsiotis" was acting in an area from Gevgelija and Stromnitsa (now Strumica) to Doirani, Polykastro and Aspros.

Georgios Koukogiannis from Metamorphossis with Asterios Demou and Lazaros Doitsinis from Evzonoi were defending their villages by Bulgarians.

Konstantinos Argyriou from Polykastro with Traianos Antoniou and Demetrios Giovanis from Axiochorion were fighting and organising the Greek schools.

Refugees who had arrived on the Southern Sporades islands, and had subsequently been transported to Athens or Thessaloniki would then make their way to the border at Idomeni to the north of Polykastro, often passing by the town on the highway.