How scholars explain Shiva's rise

Historians of religion draw a line between the Shiva of worship and the Shiva of history. On the historical side they see a slow gathering: the Vedic Rudra, a fringe god whom Flood suspects of non-Vedic roots, is lifted to sole lordship in the Shvetashvatara Upanishad; in the following centuries, as Vijay Nath puts it, countless village and regional gods became Shiva simply by taking an -isha or -ishvara ending on their names. Ascetics devoted to him appear in Patanjali's grammar commentary of the second century BCE. The Puranic Mahadeva, with his full family and his temple map, comes later still, and even the Shiva Purana's oldest surviving chapters date from around the tenth century. None of this touches the tradition's own account of him as unborn; it explains the shape of the record, not the god.