Ghiyas-ud-Din Zain-ul-Abidin(reigned: 1418–1419 and 1420–1470 was the eighthsultanofKashmir. He was known by his subjects asBud Shah(the Great King).

The first thirty-five years of his reign are described byJonarajain theRajatarangini Dvitiya, while the subsequent years are described by Jonaraja's pupil,Srivara, in theRajataranginiTritiya.

Shahi Khan, a son ofSultan Sikanderthe ruler of Kashmir, was charged with the rule of the kingdom of Kashmir when his elder brother, Ali Shah, left the kingdom on a pilgrimage toMecca. It was at this time that Ali Shah gave Shahi Khan the title of Zain-ul-Abidin. Although a religious man, Ali Shah was weak-willed and his desire to attain Mecca buckled under descriptions of the arduous journey ahead. He abandoned his pilgrimage when he arrived at the court of his father-in-law, the king ofJammu, and raised an army consisting of soldiers from Jammu andRajauriin order to regain his throne. The ancient texts vary regarding why it was that Zain-ul-Abidin relinquished his recently acquired status without a fight but there is no disagreement that this is in fact what happened.[3]

Retiring toSialkot, Zain-ul-Abidin sought the support of its chief,Jasrat Khokhar. Ali Shah became angered when this support was forthcoming and he rashly set out with his army to challenge Khokar. The forces met atThannaand Khokhar defeated the challenger, who had ignored the advice of his father-in-law to hold back until the Jammu army could join him. Zain-ul-Abidin was then able to return to the capital city ofSrinagar, where he was welcomed by his subjects. The fate of Ali Shah is uncertain: he may have died in captivity or have been put to death by Khokhar.