Siddhartha Gautama never wrote down his teachings.
Nagabashi Tomio has written: 'Practice and teachings of Shingon Buddhism (Shingonshu Raidenha)'
Buddhism was founded by Siddhartha Gautama who is widely known as "The Buddha," which means "the awakened one." He lived to be 80 years old and died around 400 B.C.E. After his death, his teachings were transmitted orally and eventually written down. Buddhist practitioners follow those teachings to this day. .
Elizabeth Armstrong Reed has written: 'Primitive Buddhism, its origin and teachings' -- subject(s): Accessible book, Buddhism 'Daniel Webster'
Chen-chi Chang has written: 'Teachings of Tibetan yoga' -- subject(s): Tantric Buddhism, Yoga 'The practice of Zen' -- subject(s): Zen Buddhism
Buddhism grew from the teachings of Siddhartha Gautam, the Buddha (hence BUDDHism). Some of his main teachings were karma, the Four Noble Truths and the Eightfold Paths.
Buddhism
The Buddha's teachings were transmitted orally for centuries before being written down. There are thousands of pages of such scriptures. In addition, many of the major figures of Buddhism have written books. For example, two classics are Nagarjuna's MULAMADHYAMAKAKARIKA [THE FUNDAMENTAL WISDOM OF THE MIDDLE WAY] and Shantideva's THE WAY OF THE BODHISATTVA. .
It would depend on how you define 'religion'. I see religion as a means of preserving teachings in the form of verse (oral or written). This might incorporate rites and rituals as the teachings are passed down. So, in answer to your question, I'd say it was after the second or at the third council (~220 BC) when distinctions between reverential, doctrinal and disciplinary practices started to appear. But this is when religion becomes sectarian.
Nyanatiloka has written: 'Essence of the Buddha's teaching' -- subject(s): Teachings 'Wort des Buddha' -- subject(s): Accessible book, Buddha (The concept), Buddha and Buddhism, Four Noble Truths, Buddhism
Siddhartha Gautama is the Buddha and the founder of the teachings that comprise Buddhism.
The greater variation in the teachings of Buddhism compared to Hinduism can be attributed to the decentralized nature of Buddhism. Unlike Hinduism, which has a more centralized structure with texts like the Vedas and Upanishads, Buddhism has multiple schools and traditions that have developed over time, each with its own interpretations and practices. Additionally, Buddhism spread to different regions with diverse cultural influences, leading to further variations in teachings and practices. This diversity in Buddhism reflects its adaptability to different cultural contexts and the emphasis on personal experience and interpretation in its teachings.