There is very little information known about Hashut. What is known is that Hashut was a powerful daemonic lieutenant of Khorne who rebelled and was trapped underground to await Khorne's punishment. The daemon was discovered by the Dwarf clans who traveled east to the Mountains of Mourn, and tunneled deep into the mountain cage of Hashut to protect themselves during the first Great War against Chaos. Hashut protected the Dwarfs who had inadvertently released him, sheltering them from the great war in the outside world.
After this a great schism split the Dwarfs, some staying true to the Ancestor Gods, and many choosing to worship Hashut. Hashut granted the most powerful of his new worshippers magical powers to use against their kin, some would eventually become so mutated that they became Lamassu or Great Tauruses - battle beasts still used by the Chaos Dwarfs to this day. After the two sides had battled, many of the traditionalists were sacrificed to Hashut, thrown into forges and furnaces. The worship of Hashut changed the nature of the original Dwarfs until, over time, they became Chaos Dwarfs, corrupted by their prolonged exposure to a powerful chaotic entity.