During the so-called Classical Period (500 B.C.E.-500 C.E.) especially, various denominations developed their own distinctive sacred texts called sutras (“threads, aphorisms”), shastras (“treatise, rule”), and agamas (“what has come down”). Sutras often take the form of commentary on earlier major texts and are major sources for the six philosophical schools called the darshanas. Some philosophical texts are called shastras, but this category is best known as a vehicle for treatments of religious law. Agamas belonging to the various sects often include various types of material ranging from the mythic to the epic to the philosophical. Shaivites generally use the term agama to describe their twenty-eight canonical works, while Vaishnavite communities often call their unique scriptures samhitas (“collections”) and Shakta groups prefer the term Tantra.