The origin of Bauls is not known exactly, but the word "Baul" has appeared in Bengali texts as old as the 15th century. The word is found in the "Chaitanya Bhagavata" of Vrindavana Dasa Thakura as well as in the "Chaitanya Charitamrita" of Krishnadasa Kaviraja. Some scholars maintain that it is not clear when the word took its sectarian significance, as opposed to being a synonym for the word "madcap, agitated". Bauls are a part of the culture of rural Bengal. Many attempts have been made to ascertain the origin of Bauls but there is wide disagreement among scholars. But they agree that no founders have been acknowledged either by Bauls themselves or others. Bauls are divided into several named groups, each following a named Hindu or Muslim guru. Besides, there are other communities who later identified or affiliated themselves with Bauls, like "Darbesi", "Nera" and two sub-sects of Kartabhajas — "Aul" and "Sai". The Bauls themselves attribute their lack of historical records to their reluctance to leave traces behind. Dr. Jeanne Openshaw writes that the music of the Bauls appears to have been passed down entirely in oral form until the end of the 19th century, when it was first transcribed by outside observers.