A Nepalian image of kAlachakra and vishvamAtA. While the emanation of the primordial cosmic buddha, the two deities were modeled after the shaiva bhairava-bhairavI-yAmala. The kAlachakra tantra, promulgating their worship, was the last great bauddha tantra to be composed (=revealed for insiders) in India. It is believed to have been composed in ~1000s-1100s as the ravages of the Meccan demons, which it records, started unfolding in the north of the subcontinent. As the well of the bauddha-mata was being defiled in the subcontinent (to paraphrase Andre Wink) and its vast Central Asian lands were falling to the tAyin-s or mlechCha-s, it was a religion in crisis (especially its vajrayANa stream).
Yet, this stress gave rise to its most expansive and inclusive expression in the cult of kAlachakra. It became an international phenomenon (to paraphrase the American Buddhologist John Newman) that acquired widespread following across the vajrayANa world. Facing an existential crisis, it tried to half-heartedly make peace with its progenitor, the sanAtana-dharma, much like an errant child running back to its parents.+++(4)+++ This was seen in its vision, where it tried to incorporate the H vision of the coming of kalkin on one hand and, on the other, the H deities in a positive sense into its eschatology.
The shaiva inspiration is seen in the below icon where the central yAmala deities of the cult are flanked by two “vajrified” bhairava-s, mimicking the shaiva iconography of flanking figures like gaNanAtha and vaTuka, or nandin and mahAkAla. However, it retains the old vajrayANa antipathy towards the shaiva-s by showing the deities trample rudra and kAma.
In a similar vein, the immortal rudrian figure of the mAhAbharata, ashvatthAman, is said to join hands with the marUnmatta-s in the final apocalyptic encounter between the forces of kalkin raudra chakrI and them. Like many modern H, it believed that a comprehensive social reform would accompany its vision of the unification of the bauddha and sanAtana dharma-s – society free of caste.+++(4)+++ This caste-free society with everyone unified under the vajra banner is believed to survive the marUnmatta-s in Central Asian refugium, from where it would liberate India and usher the kR^itayuga.