What was a significant factor contributing to the rapid growth of Buddhism in ancient India?

Dissatisfaction with existing religious practices

Buddhism experienced rapid expansion both during the Buddha's lifetime and in the aftermath of his passing. This growth stemmed from its resonance with individuals disillusioned by prevailing religious customs and perplexed by the swift societal transformations unfolding. The significance attributed to ethics and principles over assertions of superiority based on birth, along with the stress on metta (empathy) and karuna (compassion), particularly towards those who were less privileged or vulnerable, were concepts that attracted both men and women to the teachings of Buddhism.