Tantric Buddhism is a branch of Mahāyāna, generally denoted by the terms “Mantrayāna” or “Vajrayāna.” Whereas according to Buddhist tradition all Buddhist Tantras had been taught by the Buddha, according to the historical view of modern scholars the literature of Tantric Buddhism ranges from the 3rd to the 11th century CE. The Kālacakratantra and its commentary Vimalaprabhā (10th or 11th century CE) were probably composed against the background of the Islamic invasion. The paper explains how this Tantra undertakes a two-fold task: a refutation of the Vedic tenets advocating the Dharma that supports a hierarchy based on caste, class and so forth and a confrontation with the newly arrived Mleccha Dharma. The chapter shows how the Tantra attacks the advocates of the Sanskrit language and the scriptures of the adherents of Vedism, the Vaiṣṇavas and the Śaivas, that discriminate people of the four varṇas on the basis of their birth. Vimalaprabhā further refutes the very notion of the divine origin of the four varṇas. The Tantra deliberately uses ungrammatical forms and construction in order to eliminate the ego or obsession with pure language on the part of people belonging to high castes and classes.