You are not going to have an easy time finding an absolute answer to this question for two reasons, both dealing with the nature of Buddhism and Hinduism:

A. Though rooted in oral tradition (the Sutric Canon for Buddhism and the Vedas for Hinduism) they are religions of literacy and ultimately spread through writing...

B. ... which made them good tools of state expansion and control, leading to more records (and more detailed history) and the absorption of local cults into their own framework.

Without either of these things, "Asia" (which it should be acknowledged is an overreaching, western-created designation) is a collection of civilizations with oral cults around local concepts and ideas that would be difficult to translate into non-academic language. Things would get so particular that the only way to speak generally about a continent of disconnected, oral-based cults would be to say they were "pagan" with all of the vagueness that that implies. As soon as we reach down into the specifics, any similarities between systems break down. I'll just point to a few examples:

Sam Van Schaik's Tibet: A History describes how pre-Buddhist Tibet had an odd custom of mutilating one's own body upon the death of the king. A practice that is repeated (so he claims) in Greco-Roman descripions of the Scythians and Huns, implying a connection in their religious practices.

In Andrew Skilton's A Concise History of Buddhism, he describes how the Harappan civilization (famous for the sites of Mohenjo Daro and Harappa for which it is named) left behind seals used in trading sites and port locations depicting "a masked human figure in a yogic posture, though by some to be performing a primitive form of yoga or meditation." As far as I'm aware, the decline of the Harappan Civilization is still not totally understood, but their remains were defeated and assimilated into the Aryan society that would go on to form the basis of what we now know as Indian Civilization, leading to the Vedic cults first, the setting down of the Vedas in Sanskrit, and finally the development of Hinduism. It is likely, though probably impossible to prove completely, that local cults in both north and south India were absorbed into the Vedic and Hindu worldviews (i.e. the people of South India are not Aryan in language or history, but share their philosophy in the historical era).

I’m aware that the Chinese had always been philosophical in regards to Taoism and confucianism

Well, Taoism and Confucianism (according to traditional histories) arose at the same time as Buddhism. Chinese life prior to their advent was ruled by ritual practices and attempts at divining and understanding the will of Heaven, first through plastromancy (divination through tortoise shells, a practice which has parallels in the pyromancy and osteomancy practiced by societies, usually with sheep bones, all around the world. A practice we can attest as late as Chingghis Khaan in the 13th Century) and later through the Yijing. While I think it would be incorrect to call Confucianism and Taoism "atheist" because of their understanding on how the will of heaven works, their understanding of how deity and the supernatural work deos have its roots in earlier concepts which one might be able to read into the Yijing which predates them by centuries. You can read a bit about their pre-Warring States development in Richard J. Smith's Fathoming the Cosmos and Ordering the World, but that is not a book for the faint of heart (his I Ching: A Biography is a much easier text to get through, but has precious little information of relevance to your question). S.J. Marshall in The Mandate of Heaven describes the writing and creation of the Yijing, also in academic language and with a critical eye to the later stories told about the text.

although what about the rest of Asia/south east Asia? Were they simillar to most other prehistoric societies with paganism and rituals? Or were they simillar to Chinese? With atheistic philosophy?

First, how different the pre-Qin Chinese were from "most other prehistoric societies with paganism and rituals" is up to debate since pre-Qin society was certainly not atheistic in practice and very much featured a host of pagan gods and society ground to a halt with all of the rituals that had been imposed by the ruling class.

That said, the Tai people migrated to Thailand in the 10th Century (originally from southern Chinese highlands). The dominant culture and language in Vietnam is descended directly from southward Chinese migration. The people who would eventually become the Burmese have existed in that region for a much longer time, but their society became heavily Buddhist from a fairly early period of recorded history, and a similar early adoption of Indic philosophies (first Vedic, later Buddhist) also came to Cambodia, and the earliest recorded history of (what we now know as Cambodia) comes from later Chinese records of the region. All this to say that when it comes to Southeast Asia, these are open questions (see the very beginning of this post) because recorded history either begins after or because of the post-Vedic/Buddhist periods of these countries.

It's also worth noting that southeast Asia is and incredibly diverse region. I specialize in Tibet, and can talk at length at the diversity of the tradition not just within Tibetan Buddhism, but in the pre-Buddhist religion(s) of Bon. I don't think it's a crazy leap to say that Burma, which shares a linguistic-cultural root with Tibet, probably had a similar religion to pre-Buddhist Tibet. But that statement has a constellation's worth of asterisks:

• The Bon tradition we identify today has adopted sooo many features from Buddhism, the foreign religion that came to dominate Tibet for 99% of its recorded history.
• The Bon tradition prior to the 1800s was not identified as such, and common Tibetans practiced both Buddhist and bon (lower case b) rites without a theological conflict.
• Width-wise, the Bon tradition itself is incredibly diverse, and the practices of a bon shaman in Ladakh c. 700 CE could have little to nothing to do with the concept of religion of a bon priestess in Haa at the same time. So to say that bon shares a common root with the Tibetan native religion as it might with the pre-Buddhist Burmese paganism, is like what van Schaik said above about funerary practices implying a common link... but that's pretty much where any certainty ends.

The borderland between what we now call southern China and the southeast Asian states (Burma, Laos, Vietnam) are also mountainous and have been a host to tribes that sought to escape state control (the Zomia hypothesis of James C. Scott's The Art of Not Being Governed). Whether or not you agree with this hypothesis, the truth of the matter is that there are many, many tribes in the region who were historically out of the control of the governments of Burma, Thailand, China, and India but are today under their borders: the Nagas, the Lhoba, the Brokpa, the Kachin, the Naxi, to tribes that I only know by name or not at all. These tribes have their own traditions, histories, and religions that predate their later adoptions of Buddhism, Hinduism, or Christianity, often mixed with absorptions of their earlier traditions. I.e. the Naxi are majority Tibetan Buddhist (Kagyu in particular), but also have a tradition that seems to be imported from Bonpo beliefs and understanding called "Dongba." The Nagas used to be headhunters, with a complex chronology of gods and understanding about how spiritual power was transferred from heads taken by the hunters, only to be later banned and destroyed when Christianity (in particular, Baptist) dominated the religion of the Indian State.

A comprehensive of pre-Buddhist, pre-Vedic, and pre-Chinese religion in Asia is, by its very nature, impossible. Or at the very least, so granular as to be nearly meaningless in its inception. The pre-Vedic beliefs of the Tamil people, for example, would have nothing to do with Shinto practice pre-Kojiki, or the Naxi prior to their converstion by the Karmapa Lama. It also dips into anthropological understandings of the practices of particular people, without having much to do with history as we understand it (i.e. documented events and understandings, which for the most part, don't really exist prior to the Buddhist or Hindu framework in these parts of the world).