Theory:

Kanchipuram is also called Conjeeveram. Kanchipuram is situated in northern Tamil Nadu. It is located on the bank Palar River, about 25 miles east-southeast of Arcot, and on the road and rail routes between Chennai and Bengaluru.
Kancheepuram was a hub of schools. It was also a major education centre, and the first school proper regular schools were established here.
Kanchipuram is one of the most ancient cities of south India and traces its history to the \(2nd\)century \(BCE\). It also played the role of early Chola capital.
 
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Map showing the extent of the Chola empire (1100 AD)
Kancheepuram also served as the capital of Pallava dynasty from the \(3rd\) to the 9th century. From the 10th to the 13th century, it served as the later Chola headquarter.
South_India_in_AD_700.jpg
Kanchipuram under Pallavs (700 AD)
 
Kanchipuram was an important Vijayanagar town. Marathasand Muslim armies conquered Kancheepuram in the 17th century, and later by the British in the 18th century, after that the French raided it twice.
The Chinese traveler Hieun Tsang, who studied at Nalanda university visited Kancheepuram. He compared Kanchi with sacred places like Budh Gaya and Sanchi.
Great scholars such as Dharmabalar, Sumathi, Jothibalar and Bodhi Dharmar were born here. The great poet Kalidasa says, "Kanchi is the best of the towns". Similarly, Tamil poet Thirunavukarasar describes Kanchi as "Kalviyil Karaiillatha Kanchi".
Kanchi remained an important pilgrimage centre, for example, the Kailasanathar temple built by a Pallava king Rajasimha.
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Kailasanathar Temple, Kanchipuram (Kanchi)
 
Kanchipuram as Religious center:
 
Kanchipuram was once a Jain and Buddhistcenter of learning. A Buddhist monk Manimegalai took her last breath here, considering this as a holy place of the God. The great Hindu philosopher Ramanuja was educated here. Kancheepuram is also known as one of the seven great sacred Hindu cities in India, and it contains \(108\) Shaiva and \(18\) Vaishnava temples.
 
In ancient Tamilagam other than Kanchi and Poompuhar, there were also other towns such as Musuri, Thondi, Uraiyur, Karuvur, Mamallapuram, Thanjai, Thagadoorand Kaayal.
Reference:
1. https://commons.wikimedia.org/wiki/File:South_India_in_AD_1100.jpg
2. https://commons.wikimedia.org/wiki/File:South_India_in_AD_700.jpg