In ancient times, Odisha was known as Kalinga. It was a major seafaring nation that controlled and traded with most of the sea routes in the Bay of Bengal. For several centuries, a substantial part of South Asia & Southeast Asia was under its cultural influence. The temple at Angkor Wat is a fine example of Orissan-influenced Indian architecture. Some parts of Southern and South Eastern Asia such as Sri Lanka, Cambodia, Java, Sumatra, Bali, Vietnam and Thailand were colonized by people from Odisha. In Malaysia, Indians are still referred as Kalingas because of this. Many illustrious Sri Lankan kings such as Nisanka Malla and Parakrama Bahu claim Kalinga origin.
The king who destroyed the [[Sinhalese people]Sinhalese]] Buddhist control of Northern Sri Lanka and established a Hindu Kingdom in Jaffna was known as Kalinga Magha. One theory holds that the name of the country "Siam" for Thailand is derived from Oriya/Sanskrit Shyamadesha. The Angkor Wat in Cambodia is Orissan, with local variations. Bali in Indonesia still retains its Orissan-influenced Hindu heritage.
The mention of Odisha (Orissa) dates back to 260 BC, the reign of Emperor Ashoka. While spreading the boundaries of his kingdom, the emperor reached the gates of the then Kalinga and invoked its king to fight or flee. In the absence of her father, the princess of the state took reins and fought bravely with the emperor. The war was a true massacre and the bloodshed that took place moved the emperor so much that his killing instinct was capsized. A warrior was thence transformed into a great apostle of Buddhism. Buddhism followed by Jainism held sway until after the reassertion of Hinduism in the state in 7th century AD.