Explanation: The Cholas:

They controlled the central and northern parts of Tamil Nadu. Their core area of the rule was the Kaveri delta, later known as Cholamandalam. Their capital was Uraiyur (near Thiruchirapalli town) and Puhar or Kaviripattinam was an alternative royal residence and chief port town. Tiger was their emblem. Kaviripattinam attracted merchants from various regions of the Indian Ocean. Pattinappalai, composed by the poet Katiyalur

The Cheras:

They controlled the central and northern parts of Kerala and the Kongu region of Tamil Nadu. Vanji was their capital and the ports of the west coast, Musiri and Tondi, were under their control.  Vanji is identified with Karur, while some scholars identify it with Tiruvanchaikkalam in Kerala.

The Pandyas

They ruled from Madurai. Korkai was their main port, located near the confluence of Thampraparani with the Bay of Bengal. It was famous for pearl fishery and chank diving. Korkai is referred to in the Periplus as Kolkoi. Fish was the emblem of the Pandyas. Their coins have an elephant on one side and a stylised image of fish on the other. They invaded Southern Kerala and controlled the port of Nelkynda, near Kottayam. Therefore, Musiri, Tondi, Korkai, and Kaviripattinam were ports during Sangam Period.

Source: Tamil Nadu State Board Class 11