Though the Vaishnava courtly writings in Kannada began with the Hoysala poet Rudrabhatta and the devotional song genre was initiated by Naraharitirtha, the Vaishnava movement began to exert a strong influence on Kannada literature only from the 15th century on. The Vaishnava writers consisted of two groups who seemed to have no interaction with each other: the Brahmin commentators who typically wrote under the patronage of royalty, and the Bhakti (devotion) writers (also known as haridasas) who played no role in courtly matters. The Bhakti writers took the message of God to the people in the form of melodious songs composed using folk genres such as the "kirthane" (a musical composition with refrain, based on tune and rhythm), the "suladi" (a composition based on rhythm) and the "ugabhoga" (a composition based on melody). Kumara Vyasa and Timmanna Kavi were well known among the Brahmin commentators, while Purandara Dasa and Kanaka Dasa were the most notable of the Bhakti writers. The philosophy of Madhvacharya, which originated in the Kannada-speaking region in the 13th century, spread beyond its borders over the next two centuries. The itinerant haridasas, best described as mystic saint-poets, spread the philosophy of Madhvacharya in simple Kannada, winning mass appeal by preaching devotion to God and extolling the virtues of "jnana" (enlightenment), "bhakti" (devotion) and "vairagya" (detachment).