Rock Music in Sri Lanka dates back to the early 1970s when Kumar Navaratnam and friends staged the first Rock Festival at the Havelock Park in Colombo Sri Lanka. Kumara Navaratnam could be hailed as the Main strength behind the evolving rock music scene then along with others like
Prins Jayaratnam and the Unwanted Generation, Prasanna Abeysekara's Coffin Nail, Neville of Acid, Gobbledegook and Sweetie Pie, which was led by pianist Nimal Goonawardane, Richard Simon, Mary etc.
Mary was the only Rock band to play all original music at that time and was led by Ravi Balasooriya of "Bugs" fame. Other members being Aruna Siriwardane, Benjy Ranabahu, Diliup Gabadamudalige and Dwight Van Gramberg. Ramesh Weeratunga, who was a composer/solo performer of this period, went on to become a professional musician/song writer in Germany, releasing several solo albums. Sri Lanka now has a significant underground metal and hard rock community, which is growing in popularity among upper-middle-class teenagers and young adults. Some internationally known Sri Lankan metal bands include Stigmata, Chitral Somapala, Whirlwind, Old Castles Massacre, Funeral In Heaven, Forlorn Hope, Plecto Aliquem Capite, Paranoid Earthling.
The main rock radio station in Sri Lanka is 'TNL Rocks', which is a very popular radio station among the youth of Colombo, Kandy and some other suburbs of the island. Many other bands too have emerged ever since the 1990s making the heavy metal underground much bigger.
While Colombo is a breeding ground for many hard rock bands like Stigmata, Kandy gave birth to the pioneer Grunge outfit Paranoid Earthling, which was the first rock band to emerge from the Hill Capital. Kandy is also the stronghold for black metal bands like "Pariah Demise" "Lieu De Fault" and some doom metal bands as well.
source : wikipedia.org
These days Rock music is very popular in Sri Lanka. Some are criticize . However recently famous actor Gihan showed how Rap singers are singing and what method they used to become popular so quickly. That video you can watch here if you really need.