The Cholas initially occupied present Tanjore and Trincnopoly districts with of South India and, up to the eight century A.D. the Chola kingdom was very small. However, the Cholas rose to prominence when in 850 their ruler Vijayalaya defeated the Pallavas and snatched Tanjore from them, making it the capital of the Chola kingdom. Aditya Chola dynasty defeated the last Pallava ruler in 987 A.D.and the Cholas later captured Madurai from the Pandyas who had controlled the lower tip of the peninsula from early times. Rajaraja (985-1014) extended Chola domination throughout South India and Sri Lanka, and challenged the Chalukyas who had controlled the north-eastern Deccan. His son Rajendra Chola conquered the Andaman and Nicobar islands and advanced past the Ganges up to Bengal, assuming the title of “Gangaikonda” (the victor of Ganges). The powerful Chola state was now prepared to contest the maritime supremacy of Sri Vijaya Saliendras.
At the dawn of the eleventh century, inscriptions indicate that ties of friendship still existed between the two empires, but it was only to be expected that the Chola kings should resent, and eventually seek to break, the commercial monopoly claimed by the Maharajas of the Straits. What finally precipitated the conflict between them is unknown. Possibly Sri Vijaya was restricting Indian trade with the Archipelago and China, or possibly the Cholas simply felt themselves strong enough to assert their undoubted maritime strength in a digvijayaydtra through foreign territory. Whatever the cause, in c. 1025 Rajendra I mounted a great raid against the Sri Vijaya empire, a record of which is preserved in a praiasti inscribed on the south wall of the Rajarajesvara temple in Tanjore:
Rajandra despatched many ships in the midst of the rolling sea and caught Sangrama - Vijayottungavarman, the king of Kadaram (Kedah — one of the states in Malay Peninsular). Together with the elephants in his glorious army, he took the large heap of treasures which that king had accumulated and captured the arch called Vidyadharatorana at the war-gate of his extensive capital; Sri Vijaya (Palembang) with the jewelled wicket-gate adorned with great splendour and the gate of large jewels; Pannai (the east coast of Sumatra) with water in its bathing ghats; the ancient Malaiyur (Jambi) with the strong mountain for its rampart; Mayirudingam (on the Isthmus of Kra), surrounded by the deep sea as by a moat; Ilangasoka (Langkasuka/Patani), undaunted in fierce battles; Mappappalam having abundant deep water as a defence; Mevilimbangam guarded by beautiful walls; Valaippanduru, possessed of cultivated land and jungle; Talaittakkolam (Trang), praised by great men versed in the sciences; Madamalingam (Ligor), capable of strong action in dangerous battles; Ilamuri-desam (northern Sumatra), whose fierce strength rose in war; the great Nakkavaram (Nicobar islands) …; and Kadaram of fierce strength, which was protected by the deep sea.”
While it does appear from that desciption that the Chola expedition managed to reach the furthest-flung frontiers of the Sri Vijaya empire, it did not seem to have destroyed it. Even with their conquests in South India, the Cholas seldom displaced the ruling dynasties of conquered territories, being satisfied with just tribute. The aim of the Cholas was probably just to force the empire to open its shipping lanes. Furthermore, Sri Vijaya was some 1,500 miles distant - and difficult to control. While the Saliendra Maharaja of Sri Vijaya may have acknowledged the overlordship of the Cholas and opened the Straits to Indian shipping for a few years, he certainly retained his independence intact.
The subsequent relations of Sri Vijaya and the Cholas were certainly not wholly harmonious. In 1068, another Chola king, Vira Rajendra, mounted an expedition which conquered Kadaram (Kedah). This was apparently on behalf of its king, and we may assume that this was a possible attempt by Kedah, Sri Vijaya’s chief peninsular possession, to secede from the Empire. Relations seem to have normalised after this, but both Empires were by now already in decline. Sri Vijaya certainly was by now preoccupied by threats from other quarters and seeing the last days of its greatness.
(Source: The Cholas), Malaysia Uncut — A Repository of Malaysian Stuff and More.)