Ptolemaida (, Katharevousa: Πτολεμαΐς, Ptolemaïs) is a town and a former municipality in Kozani regional unit, Western Macedonia, Greece. Since the 2011 local government reform it is part of the municipality Eordaia, of which it is the seat and a municipal unit. It is known for its coal (lignite) mines and its power stations. Name During the Ottoman period the city was called Kayılar (English: Kailar, Germanic: Kajilar), rendered into English as Kaïlar. This name was retained in Greek as Kailaria (Καϊλάρια) until 1927. Kailar refers to the Kayı tribe, the tribe of Osman I, the founder of the Ottoman Empire. The modern name Ptolemaida was introduced by decree on January 20, 1927, honoring Ptolemy I Soter, son of Lagus, comrade-in-arms of Alexander the Great and founder of the Ptolemaic dynasty, and his daughter Ptolemaïs, who are said to originate from that region. His statue stands in the central square of the city. History According to archaeologists, the Ptolemaida region has been occupied since 6000 BC. Neolithic period Archaeologists, in November 2005, discovered the remains of two farming villages dating back to the Neolithic period. A press report notes that such farming villages were trading centres and had a "developed knowledge of metalworking". A golden necklace dating to roughly 4500 BC was discovered on February 16, 2006. Associated Press reporter Costas Kantouris describes the item as a "flat, roughly ring-shaped [which] probably had religious significance and would have been worn on a necklace by a prominent member of society." Lately in the lake Zazari near Ptolemaida there were found 16 houses that belong in the Neolithic era due to archaeologists. These houses were in the lake and were exposed because of the decreased water level of the lake. That particular small settlement gives information about the society and the people in the Neolithic era. Archaic period In the area of Ptolemaida many archeological findings have occurred in the last 30 years due to mining operations. Ceramic artifacts, dating to the 6th century BC have been found at two sites near Grevena and Ptolemaida. Archaeologists found the artifacts at two prehistoric farming settlements. Two Ancient Macedonian graves have also been found in the area of Ptolemaida, dated from the 5th century BC. Macedonian Period In 336 BCE the area around Ptolemaida came under the control of expanding Kingdom of Macedon under Philip II. The Land of the Chords and the whole