According to Indologist Alexis Sanderson, various classes of Vajrayana literature developed as a result of royal courts sponsoring both Buddhism and Saivism. Sanderson has argued that Buddhist tantras can be shown to have borrowed practices, terms, rituals and more form Shaiva tantras. He argues that Buddhist texts even directly copied various Shaiva tantras, especially the Bhairava Vidyapitha tantras. Ronald M. Davidson meanwhile, argues that Sanderson's claims for direct influence from Shaiva "Vidyapitha" texts are problematic because "the chronology of the "Vidyapitha" tantras is by no means so well established" and that the Shaiva tradition also appropriated non-Hindu deities, texts and traditions. Thus while "there can be no question that the Buddhist tantras were heavily influenced by Kapalika and other Saiva movements" argues Davidson, "the influence was apparently mutual."