Vanniar or Vannia (Tamil: வன்னியர், Sinhalese: වන්නියා) is a title of a chief in medieval Sri Lanka who ruled the Chiefdom of Vanni regions as tribute payers to the Jaffna vassal state. There are a number of origin theories for the feudal chiefs, coming from an indigenous formation. The most famous of the Vanni chieftains was Pandara Vannian, known for his resistance against the British colonial power.
The word Vanni may have been a derivation of the Tamil word vanam, meaning "forest", with Vanniar meaning "person from the forest".
Medieval Tamil chronicles such as the 18th-century Yalpana Vaipava Malai and stone inscriptions like Konesar Kalvettu recount that the Chola royal Kankan, a descendant of the legendary King Manu Needhi Cholan of Thiruvarur. Chola Nadu, restored the Koneswaram temple at Trincomalee and the Kantalai tank after finding them in ruins. He visited the Munneswaram temple on the west coast, before settling ancient Vanniars in the east of the island. According to the chronicles, he extensively renovated and expanded the shrine, lavishing much wealth on it; he was crowned with the ephitet Kulakottan meaning Builder of tank and temple.
Further to the reconstruction, Kulakottan paid attention to agricultural cultivation and economic development in the area, inviting the Vanniar chief Tanniuna Popalen and families to a new founded town in the area Thampalakamam to maintain the Kantalai tank and the temple itself. The effects of this saw the Vanni region flourish. The Vanniars were brought here by this chief to make make the cultivate in region.