The glory of Kelaniya reached its zenith in the Kotte period. Kelni Vihara became the closest principal shrine to the capital. So it received the patronage of the king and the people. The chief priest of the temple at this time was Vilagamulla Sri Parakrama Sanga Raja. Under him the Kelani Vihara rose to fame as a celebrated seat of Buddhist learning.
Both the temple and the city received ample royal attention. Parakrama Bahu the VI effected extensive renovation, added new edifices and developed the city. The beauty and the splendour of the city with its temple inspired many a writer of prose and poetry, during the period. Out of the many literary works of that era the Selalihini Sandesaya by Thotagamuwe Sri Rahula Thera receives special acclaim. It gives a very authentic disruption of the temple as it existed then.
Evidence shows that the vihara then was spread through a more extensive proportion of land than it is today. There have been several more edifices than there are found today. We find them all specifically described and appreciated in Sri Rahula Thera’s poetic work. A few of these ancient edifices were the Samadhi Pilimagaya, Thivanka Pilimagaya, Sivurudageya, and Telkateragaya.
During the middle of the fifteenth century the fame of Kelani Viharaya as a seat of Theravada Buddhism reached its orient. Hence during the reign of King Buvanekabahu VI, King Ramadipathi of Burma (the present Miyanmar), sent a bikkhu mission to Sri Lanka. He sought the assistance of the Sinhala kings to reinstitute the Theravada ordination in his country, which had become extinct in Burma due to the internal conflict and disorders within the land. After reuniting the country and restoring peace the Burmese king set about organizing the religious order.
Thus on the advice of Moggallayana Thera, the Snganayake of Burma, the king sent 45 Bhikkuhus to Sri Lanka to receive the Therawada System of ordination. He even set-up an embassy in Sri Lanka headed by two of his ministers Ramdutha and Chitradutha. King Buwanekabahu received them with due honour. The king consulted his ministers and the Sangaraja of Sri Lanka, regarding the request of the Burmese King. Twenty four of great learning and repute were selected from among the Sangha Fraternity of Sri Lanka to officiate at the ceremony and the ceremony was held at the auspices of the Kelani Viharaya.
A canopy was set up on boats hitched together at the Kelani River, which is next to the Temple, as the venue for the ordination. Vidagamsa Maha Thera of the Kelani Viharaya performed the ordination ceremony to admit the s temple by the Burmese monks to the Theravada Fraternity. The King himself made very valuable offerings to the Burmese monks, and gave them each a new name of Sinhala origin.
When they returned to Burma King Ramadipathi was very pleased. So pleased that he built a chapter house and named it Kelani Sima and recorded the history of this mission on slabs of marble. These slabs are preserved to this day and are known as Kelani Inscription.
The region of King Dharma Parakramabahu of Kotte is noted as one of the most memorable periods in the history of Kelani Vihara. In the 19 th year of his reign, he carried out extensive restoration work at the temple. After completing the work he set up an inscription, recording all that, on a large slab of granite. This inscription which is preserved to this day can be seen at the temple premises. However it is now in thirteen pieces as it had not escaped the wanton destruction caused to this temple by the Portuguese in late 16 th century.
This inscription describes in detail this renovations carried out by the king at the temple premises, through the agency of his minister Vijaykkonara. It specifies the several shrines that existed within the temple purlieu and declares the boundaries of the lands attached to the temple. It further states that the title of Sri Rajaratna Pirivena Thera was conferred on the incumbent of the temple of that time. Apart from this, the king was so fascinated with the beauty of the place that he built a five- storied palace, for his residence, on the further bank of the river in clear view of the temple. The kings of Kotte in latter years used this as their summer residence.