Ala-ad-din Tarmashirin Khan (Chagatai and Persian: علاء الدین; ruled 1331 AD - 1334 AD) was the khan of the Chagatai Khanate following Duwa Timur.
His conversion to Islam did not go down well with his Mongol nobles, who were overwhelmingly Tengriist and Buddhist.
Because Tarmarshirin preferred to dwell in cities of Transoxiana, he was accused of abandoning the traditional Mongol code of conduct, Yassa, and was deposed in the horde's annual kurultai.
Muslim sources have always portrayed Tarmashirin in a very favorable light owing to his seminal effort in bringing Islam into eastern Asia.
The famous Muslim explorer and scholar Ibn Batuta had visited the khan during his travel through Tarmashirin's realms.