Part 1

This is, of course, a huge and very complex topic with no simple answer so much as gradual developments. There are a few notions here: the notion of Hinduism as opposed to other religions, in contrast the unity of so much of Indian religion and how it absorbed many other groups, and what we mean by the notion of ‘a religion’ itself.

Ancient India didn’t speak of ‘Hindu’ identity. ‘Hindu’ is a Persian word (derived from their name for the Indus River, and which is cognate with the Sanskrit Sindh - the s and h correspondence being quite a regular one, eg the ritual drinks soma and haoma in Hinduism and Zoroastrianism respectively, and many other examples).

Classical India Rather, the notion in classical India was of ‘astika’ (often translated ‘orthodox’) and ‘nastika’ (‘unorthodox’) religion, with the former including traditional schools of thought which accepted the Vedas as sacred (traditionally listed as six: Mimamsa and Vedanta, Samkhya and Yoga, Nyaya and Vaisheshika), and the latter those which did not, including Buddhism, Jainism, and other now extinct movements like Ajivika. Unfortunately, actual Indian historical records open up a couple of centuries after the traditional founding of these religions (around the 6th century BC), and in fact most of the earliest detailed historical accounts (of which there are sadly few) which correspond to known states of the era are only written from Jain and Buddhist perspectives, with Hindu itihasa (‘history’) mainly confined to an earlier ‘prehistoric’ era, in large part regarded as mythic by secular historians (or ‘non-literal’ even by many Hindu ones), and rather harder to date, so it is very hard to know exactly how these different schools came about, but when the historical record opens there is a clear division between the ‘astika’ schools and the rest, and the Buddhists and Jains maintained a separate identity from this time. It’s important to note that not everything about Hinduism outside some core differences in Vedic philosophy was seen as alien to Buddhism, for example: Buddha made references to Hindu gods like Indra (seeing them as just a ‘fact of life’, but not necessarily as fundamental to his philosophy and ultimately another part of the illusory universe), and much later it was possible to keep these aspects integrated in the ‘Hindu-Buddhist’ culture that eventually spread to SE Asia: note the importance of the Ramayana in Thailand, for example, with its Buddhist kings named Rama.

But some aspects were indeed largely alien: Buddhism and Jainism specifically rejected the rigid caste system of Classical India with the religious authority largely confined to Brahmins, and in this context ‘astika’ Hinduism is sometimes even called ‘brahmanism’ - and both founders Buddha and Mahavira were in the Kshatriya (‘warrior’ or ‘kingly’) caste, not the priestly ‘Brahmin’ caste. So in this way, the split could be seen as a social revolution of sorts. There may have been some attempt to persuade or incorporate Buddhism into wider Hinduism, as a traditional list of Vishnu’s ten avatars included the Buddha as the ninth, but this is largely speculative. It is also speculated by some historians that Jainism and Buddhism may trace their philosophical roots to extremely ancient times as well, as sisters rather than daughters of Vedic or indigenous tradition, but again this goes back to a period where we just don’t know enough.

The Vedas themselves were Indo-Aryan scriptures, and arguably had a more prominent role in the Indian religion of this time, so it is ironic that . Sin

Persians The first attestation of ‘Hindu’ as a term was by the Persians in an inscription of Darius I, but a geographic/ethnic one, referring to the people of the province of the Achaemenid Empire that extended beyond the Indus, roughly today’s Punjab. It’s worth noting that this was at a time when religion was broadly an ‘ethnic’ affair: different ethnic groups split by language also had different religions, and the distinction of ‘a religion’ was not as specifically made. The word made its way to Greece, where Herodotus and later writers discuss the religious beliefs of ‘India’, often in ways that are unrecognisable today (eg, Herodotus found it notable that Indians - or possibly some of them - were averse to cremation and preferred burial, though it’s not like Herodotus is renowned for accuracy).

Since that time, Hindu philosophy has varied hugely - major new schools have arisen (the Dvaita, Advaita, Vashishtadvaita) and in crass terms, the most-worshipped gods have changed from a Vedic pantheon led by Indra to a massive focus on Vishnu and those now mostly regarded as his avatars, Shiva, Ganesh, Devi, and others - though this is not the place to trace the fascinating and extremely complicated story of how all this seems to have developed. Many smaller local ‘religions’ were absorbed into a more unified religion.

Now Hinduism wasn’t entirely unusual in the way it did this: it was common for other Indo-European and polytheistic religions, such as those in Europe and the Middle East, to regard each other as loose analogies. Greeks and Romans spoke of Egyptians, Germanic tribes etc. as worshipping ‘equivalents’ of their own gods, to the point that they simply described Egyptians as worshipping ‘Dionysius’ (in the name of Osiris) etc. In fact this is essentially how Roman religion came to essentially merge itself with Greek religion. From the time of the Greeks to the first Islamic invasions, despite occasional intrusions by Hephthalites and others, India culturally largely concerned itself with India, and outside those schools that had long been regarded as ‘unorthodox’, and certain small tribes that had minimal interaction with ‘civilisation’, many regional traditions were merged in this way with many deities being identified and leaving a legacy of many names, and the wider philosophies spreading to give some fundamental tenets about reincarnation, cyclical time, karma etc. as a common philosophical basis. But this was not seen as ‘conversion’ in the same way as Christianity or Islam would, but the promulgations of many specific ideas - and was very, very far from uniform.

Islamic Era This changed with the Islamic conquests, starting with the invasion of Sindh by the Umayyads in the 8th c. and later the invasions deeper into India in the 11th-13th centuries by the Ghaznavids, Ghurids and the groups who would become Sultans of Delhi. Abrahamic religions have absorbed some outside practices to a degree, but overall had a different and arguably more ‘absolutist’ notion of how strictly a set of tenets one must believe to adhere to the ‘true faith’, and any serious deviation meant an outsider identity. Islamic law mandated categorising the non-Muslim population very differently from Muslims (and usually unfavourably - for everything from tax purposes to marriage law), and the natural word for the religion was ‘Hindu’ - essentially, ‘Indian’, since they followed ‘Indian din’, where ‘din’ is an Arabic word generally translated as ‘religion’ but often translated as ‘law’. It is here that we see the first widespread usage of the term ‘Hindu’, though only in Islamic sources. And it is under Muslim rule that a more specifically Hindu (or at least, non-Muslim Indian) identity started to form as a reaction against religious oppression. The contrast of Hindu saffron from Muslim green, for example, dates back only to the Marathas from the late 17th-19th centuries (it is unclear when saffron first arrived in India, but it seems to have done so via Persia), from the later-imposed view that they stood for Hinduism against the Islamic empires. It’s worth noting that by this period, Buddhism barely existed in India and Jainism was as always practised by a very small minority. It was Islam that saw itself as different from the ‘native Indian’ religious movements in a way they did not see themselves as different from each other (given their general attitude of multiple truth) that caused the rest to begin to be packaged with one label.

The other group of note who stood out at the time were the Zoroastrians who fled Islamic rule in Persia, and in India came to be known as ‘Parsis’ (or ‘Iranis’, for a later group) - a tellingly ethnic description. (‘Zoroastrianism’ is a rather Western word, patterned after ‘Christianity’ and the old Western name ‘Mohammedanism’, in that it was named after a specific founder).

Continued below