The area where the town of Kardzhali is now located has been inhabited since the
Neolithic. Many
artifacts, comprising ceramics and primitive tools, have been found during the archaeological excavations. Most of them are now exhibited in the local historical museum. Later
Thracian tribes settled in the area and developed a highly advanced civilization. They built many sanctuaries dedicated to the gods of the
sun and the
earth. Near the village of Nenkovo (northwest of Kardzhali), an artificial cave was found in 2001. It has the form of a woman's
womb and is called the
Utroba Cave. Exactly at noon, when the sun is highest in the sky, a ray of light comes in through a stone slit forming a falitic shade in the cave. According to the Thracian beliefs, this is the conception of the new sun god. This cave is considered a complex
astronomic facility (compared to
Stonehenge in Great Britain) as the ray of light enters the cave on a single day of the year. There are many stone castles and palaces that the Thracians built in the region, including Perperek,
Ustra, and
Vishegrad. The most magnificent is
Perperikon, where a Thracian king resided. The place has become increasingly popular since the recent archaeological works rendered wealth of artifacts. During the
Byzantine period, Kardzhali was the center of a Christian eparchy: Achridos. During the reign of the
Bulgarian Empire, Kardzhali was known as
Zherkovo a name that was used by the Bulgarians until the 17th century. The
Monastery of John the Precursor (Bulgarian: Йоан Продром or Йоан Предтеча) was built in the 6th-8th centuries and is now a monument of medieval architecture. Apart from the fortress of Vishegrad on the right bank of the Arda, the eastern approaches of the town were protected by the medieval castle of
Monyak on the left bank of the river. A couple of other monasteries were built during this era, with some of them remaining until the early 19th century. The area was of strategic importance for the Bulgarian Empire during the Middle Ages and the remains of numerous Medieval fortress scattered on the surrounding hills can still be seen. The town developed largely due to its position on the trade routes during the period of Ottoman rule. However, it remained a small town. During the 18th century, Turkish
brigands used this remote town as a hideaway and supply point, and the town was later named after their leader Kırca Ali. The best known of these units was led by
Pazvantoğlu Osman Pasha, who ruled most of the northeastern Ottoman lands and the Danube estuary until his death in 1807. Kardzhali and its neighborhood became part of the autonomous province of
Eastern Rumelia under the stipulations of the Berlin Congress of 1878, but, after the reunification of the
Principality of Bulgaria and
Eastern Rumelia in 1885, it was ceded back to the Ottoman Empire as a township of
Gümülcine sanjak in
Edirne vilayet.
Ottoman rule ended during the
First Balkan War when the town and the surrounding area were liberated by the Bulgarian General
Vasil Delov on 21 October 1912. The day has been celebrated with concerts and commemorative events as a municipal holiday since 1937. Kardzhali was declared the center of Kardzhali Province, when it was created from the most southern part of
Stara Zagora Province in 1949. ==Demographics==