Ah, the transition period of vegetarianism in India! While it's challenging to pinpoint an exact time period, we can highlight some significant milestones that contributed to its growth.

During the Vedic period (1500-500 BCE), vegetarianism was not necessarily prevalent among all sections of society. The Rigveda, one of the oldest Hindu scriptures, mentions animal sacrifices as a part of religious rituals. However, there were also texts like the Chandogya Upanishad that emphasized non-violence and promoted a vegetarian lifestyle.

The rise of Buddhism in ancient India during the 6th century BCE played a crucial role in popularizing vegetarianism. Gautama Buddha himself advocated against animal sacrifices and encouraged his followers to adopt a compassionate approach towards animals.

Around 800 CE, Jainism gained prominence under the influence of Mahavira and propagated strict adherence to non-violence and vegetarianism. Jain communities played a vital role in upholding these principles throughout history.

With the spread of Islamic rule across parts of India from around 12th century onwards, meat-based cuisine became more prominent among certain segments. However, it is important to note that even during this period, many regions within India still maintained strong vegetarian traditions.

In more recent times with globalization and increased awareness about animal rights and environmental concerns, there has been renewed interest in vegetarian diets worldwide, including India.

So while there isn't one definitive transition period per se for Indian vegetarianship, these historical influences gradually shaped attitudes towards diet and culminated in what we see today—a substantial share of vegetarians within Indian society.