The village was the fundamental unit of administration and in connection with the management of village affairs we come across the terms: Manaram, Podiyil, Ambalam and Aval.
The Manaram, the Podiyil and the Ambalam seem to be synonymous terms denoting a place where the village assembly (Avai) met to transact local business.
The kingdom was, though not theoretically, divided into smaller units. The entire kingdom (big or small) was called Mandalam. The Chola, the Pandya and the Chera were the original major Mandalams. Nachchinarkkiyar speaks of the four divisions of Tamilaham: Chera, Chola, Pandya and Tondai Mandalams.
Below the Mandalam a major division was Nadu and we also hear of a unit called Kurram. According to V. R. R. Dikishitar, Nadu was a subdivision of Kurram and according to U. V. S. Iyer; Kurram was the subdivision of Nadu.
The Ur was a town which was variously described as a big village (Perur), a small village (Sirur) or an old village (Mudur). Chcri was the suburb of a town or village, while Pakkam was a neighbouring area. Salai was the trunk road and Teru the street in a town.
Pattinam was a term for a coastal town and Puhar was a general term for harbour area. Kaverippumpattinam was the pattinam par excellence of Tamilaham and was generally known as Pattinam only.
Many towns have been mentioned in the texts but the major ones were Puhar (the famous Chola port and coastal capital), and Uraiyur (The Chola inland capital also known as Koli and Varanam: it was a strongly defended city and its outskirts had burial grounds which were full of stones and hence 'there were many obstacles to easy movement'.
This description is strongly suggestive of the existence of the megalithic burials; the classical writers describe the place as noted for its cotton textiles-Argaritic derived from Argaru or Uraiyur, Korkai (the Pandyan coastal capital, situated on Tamraparni river; it was reputed for its pearl fisheries where the Paradavar (fisherman) dived for pearls), Kayal (meaning salt pans, situated near Korkai; the Periplus talks of Colchi (Korkai) and its pearl fisheries worked by condemned criminals), Madurai (the Pandyan inland capital), Musiri (the Chera port) and Vanji or Karur (the Chera capital). Kanchi (also known as Kacci, Kaccimurram and Kacchippetu) the capital of Tondainadir, was another major city.
Arikamedu known to the Sangam literatue as Virai (modern Viram Pattinam) is one of the most important town so far as archaeology and Roman trade is concerned. It was one of the velir strongholds known to Sangam literature. Virai, described as a harbour was probably one of the coastal town like Sopattinam (modern Marakkanam), of the Oy clan of velir it was also the capital of the velir chieftain Virai Veliyan Venman.