We have many books that were composed in north India, especially in the areas watered by the Ganga and the Yamuna, during later Rigvedic age. As these books were composed after the Rigveda, they are generally called later Vedic (or later Vedic literature). These include the Samaveda, Yajurveda and Atharvaveda, as well as other books. These were composed by priests and described how rituals were to be performed. They also contained rules about society.