The Eastern Province (Tamil: கிழக்கு மாகாணம் Kil̮akku Mākāṇam; Sinhalese: නැගෙනහිර පළාත Næ̆gĕnahira Paḷāta) is one of the nine provinces of Sri Lanka, the first level administrative division of the country. The provinces have existed since the 19th century but did not have any legal status until 1987 when the 13th Amendment to the Constitution of Sri Lanka established provincial councils. Between 1988 and 2006 the province was temporarily merged with the Northern Province to form the North Eastern Province. The capital of the province is Trincomalee.

In 1815 the British gained control of the entire island of Ceylon. They divided the island into three ethnic based administrative structures: Low Country Sinhalese, Kandyan Sinhalese and Tamil. The Eastern Province was part of the Tamil administration. In 1833, in accordance with the recommendations of the Colebrooke-Cameron Commission, the ethnic based administrative structures were unified into a single administration divided into five geographic provinces. The districts of Batticaloa, Bintenna (part of present-day Badulla District), Tamankaduva (present day Polonnaruwa District) and Trincomalee formed the new Eastern Province. Tamankaduva was transferred to the newly created North Central Province in 1873 and Bintenna was transferred to the newly created Uva Province in 1886.

...
Wikipedia