Sadruddin Shah, also known as Rinchan, was the first Muslim ruler of Kashmir. He ruled Kashmir from 1320 to 1323 and was instrumental in establishing Islam in Kashmir. He is known by different versions of his names: Rinchana, Richan, Rinchan Shah, Rinchan Malik, Malik Rinchan.
Rinchan, whose full name was Lhachan Gualbu Rinchana, was a Buddhist prince from Ladakh, and the son of the Ladakh chief, Lhachan Ngos-gruba, who ruled Ladakh from 1290 to 1320. He revolted against his uncle, the ruler of Ladakh, but was defeated and fled to Kashmir. Raja Suhadeva appointed Rinchan as a minister. A Muslim from Swat named Shah Mir was appointed as a minister in Kashmir by Suhadeva and he became good friend of Rinchan. Mongols under their leader Dulchoo, invaded Kashmir with 70,000 soldiers and defeated Suhadeva, who fled to Tibet. After the departure of Mongols, his prime minister, Ramachandra, took advantage of the anarchy and occupied the throne. He appointed Rinchan as an administrator. Rinchan became ambitious. He sent a force in the fort in the guise of merchants, who took Ramachandra's men by surprise. Ramachandra was killed and his family were taken prisoners. Rinchan became the ruler of Kashmir.
In view of his Ladakhi origin, Rinchan found it crucial to gain support to legitimize his rule. To this end, he won over Ravanachandra, the son of Ramachandra, to his side. He made him his chief adviser and gave him the title of Raina and Ladakh and Lar as his jagir. He also married Kota Rani, Ramachandra's daughter and agreed to convert to Hinduism. He approached the head guru of the Brahmin Pandits Devaswami for this purpose. However his request was spurned by the Shaivite guru who refused to accept him into the Hindu fold due to his hand in killing Ramachandra.
The Sufi missionaries from the Middle East and Central Asia had settled in Kashmir and had converted some Kashmiris to Islam. There was competition and conflict between Buddhism and Hinduism in the court of Rinchan. Shah Mir convinced Rinchan that he could choose to convert to Hinduism, Buddhism, or Islam. Shah Mir suggested to Rinchan that he could convert to the religion of the first person they encounter next morning. Shah Mir pre-planned the morning meeting with Sufi mystic Syed Sharafuddin Bulbul Shah to convert Rinchan to Islam. The next morning when they left the palace the first person they met was Bulbul Shah who was performing his morning prayers. Rinchan converted to Islam and adopted the title of Sultan Sadruddin Shah. 10,000 of his subjects, including is brother-in-law Ravanachandra, converted along with him.
After conversion, he renamed Srinagar as Rinchanpora and built a mosque known as "Bud Masheed", on the site of a Buddhist temple. This was the first mosque to be built in Kashmir. The original structure was later burnt and replaced with a smaller structure. He also built another mosque at Ali Kadal. He built a khanqah in honor of his spiritual mentor Bulbul Shah. Attached to the khanqah was a langarkhana (public charity kitchen) known as Bulbul Lankar, where the poor were fed free-of-cost there twice a day. He also granted the revenues of certain villages to him
He had a son, Haidar Khan, by his queen Kota Rani, whom he entrusted to the care of his trusted minister Shah Mir. Rinchan was attacked by rebels and was badly wounded and died in 1323. Shah Mir attacked his capital city and wanted to marry Kota Rani. Kota Rani fought bravely, but lost as her kingdom was already weakened by the Mongol attacks. She committed suicide after losing the battle.
In 1909, Rinchan's grave was discovered near Bud Masheed by archaeologist, A. H. Francke.