The municipality of Petrich is located in Southwest Bulgaria, in the administrative district of Blagoevgrad close to the borders with Greece and Macedonia. The administrative center of the municipality is the town of Petrich which is the second largest in the district after Blagoevgrad. Petrich lies in the southern part of the Petrich Hollow, at the northern foothills of Belasitsa Mountain. It is one of the oldest towns along the Struma River Valley. The settlement was founded in the time of the Thracians and some specialists believe that it was the heir of the ancient Thracian town of Herakleya Sintika, located in the crater of Kozhuh. In that locality, about 10 km from the present-day city, the tribe of Medi founded a settlement in the 4th c. BC. Three centuries later, the Romans conquered these lands and turned the small settlement at Kozhuh into a fortified town that kept the middle course of Struma River and the Rupel Gorge. Excavations have shown that the town existed until the 6th c. AD when the Slavs burnt it down. Historians assume that the spared citizens of the burnt town settled at the foothills of nearby Belasitsa thus laying the foundations of present-day Petrich.
The Petrich region joined the Bulgarian State in 837 as a result of the war of the Bulgarian Khan Persiyan against the Byzantine Empire. In the following centuries, especially the 10th and 11th c. AD, this area played a strategic role in the state of Tsar Samuil. The dramatic Belasishka Battle took place in 1014, not far from today’s town of Petrich, in the Klyuch Gorge. The army of the Byzantine Emperor Vasili II defeated the troops of Tsar Samuil and blinded the captured 14000 Bulgarian soldiers. For that, the Emperor was called Vasili the Bulgarian Slayer.
In the Middle Ages, Petrich became a stronghold – part of the fortification system of Southwest Bulgaria. That is evident from the remains of the Medieval Gyaur Kalesi (Bulgarian Fortress) above the town and the document of the ruler Konstantin Dragash who donated some Petrich estates to the Russian Monastery of Sveti Panteleymon in Athos in 1376-77. The region was conquered by the Ottoman Turks after 1395 and became part of the Kyustendil Sandjak (District). At that time, it was mostly known for its agricultural production: wheat, barley, rye, cotton, tobacco and fruits (especially chestnuts). In the period 16th – 19th c., the nearby village of Dolene hosted the famous Dolyanski Fair which happened to be one of the biggest fairs in the whole of the Ottoman Empire.
During the Renaissance Period (the so-called National Revival Period), the town and its population grew together with crafts and commerce. Many people from other towns and regions came to settle here; they all spent their time in hard labour. Struggle for the Bulgarian language, Bulgarian schools and Bulgarian church involved this region as well as others. In 1878, the town was freed but returned to the Ottoman Empire as a result of the Berlin Treaty and remained there until 1912. It was freed during the Balkan War by the regiment of Nikola Parapanov. Turkish population left together with Greek fans who settled over the border in the village of Neo Petritsi (New Petrich). Many Bulgarian refugees came to live here instead and their number reached 4500 after the Allies War.
Between 1920 and 1934, Petrich was the regional center of the so-called Pirin Macedonia. After WWI, the town had its first urban planning, electrification and construction of water supply system. The center of cultural life became the Chitalishte of Bratya Miladinovi which was accommodated in the former Turkish mosque. After the Liberation, the means of livelihood of local people remained unchanged; they lived on agriculture, stock-breeding and crafts.