The worship of Shiva is a pan-Hindu tradition, practised widely across all of India, Nepal and Sri Lanka.
Some historians believe that the figure of Shiva as we know him today was built up over time, with the ideas of many regional sects being amalgamated into a single figure.
One expert traces the origin of Shiva to the pre-Aryan period, and believes that he played an important role in the Indus Valley Civilization. How the persona of Shiva converged as a composite deity is not well documented.