Artillery allows Turkish Bombard Towers to outrange enemy Bombard Cannons, as well as making their Elite Cannon Galleons have the greatest range (17) of any unit in the game (tied with a Trebuchet with Siege Engineers researched). It also gives Bombard Cannons a larger range, making both units formidable for sieges.
"Early firearms and cannons were operated by professionals and mercenaries who worked for the high bidder. In the late Middle Ages, the high bidder was often the Turks who controlled important trade routes to the East. This gave the Turks important experience with these new weapons that they used with effect against Constantinople and other Christian citadels."