Vedism, with its orthodox rituals, may have been challenged as a consequence of the increasing urbanisation of India in the 7th and 6th centuries BCE, and the influx of foreign stimuli initiated with the Achaemenid conquest of the Indus Valley (circa 535 BCE). New ascetic or sramana movements arose, which challenged established religious orthodoxy, such as Buddhism, Jainism and local popular cults. The anthropomorphic depiction of various deities apparently resumed in the middle of the 1st millennium BCE, also as the consequence of the reduced authority of Vedism.