Asia does not mark history in the same linear evolution of monotheism as the West. Instead, early Indian philosophers developed schools of thought and encouraged debate and analysis, with the founders of Buddhism, Jainism, and Vedantists (Hinduism) developing their own interpretation and systems of application. The primary source of atheistic and materialist philosophy is attributed to Carvaka, author of the Barhaspatya-sutras. The details, of actual historical dates and sources, are sketchy and controversial, as many later schools used these early works as examples of "skepticism" in general and not as a specific school of thought.
"...regard only that which is an object of perception, and cast behind your back whatever is beyond the reach of your senses (2.108)" - Ramayana
The primary qualities associated with the Carvakas tradition is "they held truth, integrity, consistency, and freedom of thought in the highest esteem."... not unlike the modern school of atheism. Like modern atheists the Carvakas avoided "speculative metaphysics" stressing direct perception. As the Epicureans of ancient Greece, the Carvakas insisted on joyful living in a tempered manner (as apposed to the Buddhist and Jains who preferred a system of penance and sacrifice).
Doubting unverifiable phenomena, the transcendental world, life after death, and the law of karma, this school did not win many friends in the developing schools of Asian religious practice. The Carvakas also denounced the caste system as unreal, an artificial system which made no sense. Much of what we know about this school is second hand. They had many enemies, who insisted on destroying most of their written records.
Buddhism is sometimes reffered to as an agnostic philosophy, while Jainism has similarities to atheism, yet both do not easily compare with agnosticism and atheism in the West. What there is in Asia, lacking the fundamentalist climate of the monotheistic West, is a flexibility of opinion. There is in the European tradition a need to choose. In Asia we are not likely to ask "Do you accept Jesus as your personal savior" as if pronouncing a threat. Most likely people will not ask at all, but if they do have questions, it will be more from a sense of curiosity, than a sociopolitical stance.
In the East, religion is often assumed to be the affair of experts, temple priests and elders. Ritual is appreciated as an extension of life, cultural and primarily for social bonding or healing the trauma of death and disastor. Issues of life after death, the soul, and faith are subjective and only of personal consequence. The religious wars of Asia nowadays are primarily political, territorial, and cultural... India and Pakistan, Tibet and China, North and South Sri Lanka.
The political introduction of forced atheism in China, Viet Nam, and Cambodia, did little to eliminate local religious belief. In my opinion, the primary impetus behind the gradual expansion of atheistic thinking among urban professionals has been the advent of Western science and economic materialism. As rationalism and the pragmatic advantages of science succeeds in moving people to a 'modern' developed economy, while air travel and technological connectivity increases, local indigenous faiths lose some of their hold on both individuals and the community as a whole.
While affluence will help rebuild the destroyed temples of the Communist purge, placating the guilt of the nouveau riche, the genie of 'skepticism' is out of the bottle. A new sectarian citizenship, based on collective interdependence, is evolving. Community values coupled to an international ethos is emerging from our turbulent twentith century. Religion's foothold loosens, as we reach upward toward the stars with our flotilla of miraculous technology.