In the Old Indian mythology Pishachas are described as spiteful and harmful demons or vampires sending diseases, attacking people, feeding their meat and a blood and devouring corpses. In the late Vedic literature ("Ahtarva Veda") Pishachas appear as one of three classes of dark demons (together with Rakshasas and asuras), withstand to gods, people and light demons. Sometimes they are identifyed with dyeed in gold yellow colour Rakshasas and included in the suite of Shiva.
In the "Tibetian book of the Dead" Pishachas are characterized by witches with bird's (of a hawk, raven, owl, etc.) and animal (of a lion, tiger, wolf, etc.) heads and human trunks of dark-violet, deep blue, black, red and light yellow colour.
See my photos of Pishachas made in the Royal Palace in Bangkok in the section "Disappeared inhabitants of the Earth in the sculpture and painting of Thailand and Cambodia"
The data are reported that Pishachas inhabited Vindhja mounts and talked in special tongue "pishacha".
The "Maitreya Upanishada"- the part of the "Black Yajur-Veda", names Pishachas by demons-snakes.
The section "Aboriginal inhabitants"
Read my works "Great antediluvian civilizations of Fomorians, Rakshasas, Viyevichs and Nagas. General characteristic and their role in the world history" and "Giants and titans - predecessors and contemporaries of people. What was the growth of gods and demons?"