"In the Vedic cosmic hierarchy, there is a graded series of higher planetary systems, each of which is inaccessible to the inhabitants of the systems below it. The topmost authority in the material universe is known as Brahma, and he lives in the highest material planetary system, called Brahmaloka. Beneath Brahmaloka there are the planetary systems Tapoloka, Janaloka, and Maharloka, which are inhabited by sages (rsis) who live as ascetics and cultivate knowledge and transcendental consciousness.
"Beneath these planets, there is the realm of Svargaloka, which is predominated by the beings known as Devas. The Devas are organized in a military hierarchy. They engage in politics and warfare, and their battles with lower forces may sometimes have an impact on life on the earth. However, due to the extremely long life spans of the Devas [hundreds of millions of years], their social and political relationships tend to be stable."

"The most famous rebels are the Asuras, who are close relatives of the Devas. The Puranas describe protracted wars in Svargaloka between the Devas and Asuras, and the basic plot of the Mahabharata has to do with an invasion of the earth by the Asuras.
"Since the Devas are beings of a godly nature who hold administrative posts in the universal hierarchy, the word 'demigod', which in classical Roman times meant a being intermediate between the demigods and man. The Romans and Greeks thought that there were many types of beings in this category, and these were not all regarded as evil or 'demonic'. The Vedic literature also describes many races intermediate between the Devas and human beings, and these include the Vidyadharas, Uragas, and Raksasas.
"The Raksasas are demonic and highly inimical to humans. The Vidyadharas and Uragas are essentially neutral - they cooperate with the universal hierarchy, but they have their own agendas to pursue, and they neither favor nor oppose the human race. They belong to a category of beings known as Upadevas, or almost-Devas."

"According to Vedic understanding, different races of humanoid beings tend to be predominated by different combinations of the three modes [sattva - 'pure beingness', rajas - passionate desires, tamas - 'darkness' and delusion]. Thus human beings of this earth tend to be predominantly in the mode of passion, with some admixture of goodness and ignorance. The Devas and Rsis of higher planets are predominantly in the mode of goodness and thus, in comparison with ourselves, they tend to be very peaceful and attracted to knowledge.
"Among the Vedic humanoids, there are a number of groups that are predominantly in the mode of ignorance. These are broadly known as Bhutas (a term which, appropriately enough, can be translated as 'entities'). They include the Pisacas, Yaksas, Raksasas, and Vinayakas, as well as the Dakinis, Yatudhanis, and Kusmandas. These beings are said to live in subtle form on the earth and in the region immediately above the earth's atmosphere. They are known for their mystic powers, including the power of suddenly appearing and disappearing in gross material form.
"It is said in the Bhagavanta Purana that these beings are known for causing trouble to the body and the senses. They also cause of memory and bad dreams, and they are said to be particularly troublesome for children."
     - Richard L. Thompson, Alien Identities - Ancient Insights into Modern UFO Phenomena

Hyperlinks

·The Apocryphic Book of Enoch
·Secrets of the Vimana