Some scholars assert that Ayurveda originated in prehistoric times, and that some of the concepts of Ayurveda have been discovered since the times of Indus Valley Civilization and earlier. Ayurveda significantly developed during the Vedic period and later some of the non-Vedic systems such as Buddhism and Jainism also developed medical concepts and practices that appear in the classical Ayurvedic treatises. Humoral balance is emphasized, and suppressing natural urges is considered unhealthy and claimed to lead to illness.