The Tayichiud (Cyrillic: Тайчууд) were one of the three core tribe Khamag Mongol confederation in Mongolia in 12th century. Though Khiyad Borjigids and Tayichiuds were closely related and shared a common ancestry Bodonchar, at times they were arch rivals for the rule of Khamag Mongol. Though Khabul Khan of Borjigin had 7 sons, he nominated Ambaghai, a son of Sengun Bilge from Tayichiud, as his successor. Thus, Ambaghai Khan become second khan of Khamag Mongol. The rule of the Mongols exchanged between Borjigid and Tayichiud tribes, finally coming into the hands of Genghis Khan of Borjigid.
The Tayichiud were rivals of the Naimans and several other tribes. In the Secret History of the Mongols, they are portrayed as bitter enemies of Genghis Khan. As allies of Jamukha and the Keraits, they could defeat the latter bitterly.
Although ruling Tayichiud clan was destroyed by Genghis, their descendants, who surrendered, achieved fame in parts of Mongol Empire. Jebe (born Jurgaadai), who struck the final blow to the Jurchens in Manchuria in 1219 and defeated Kypchaks and their European allies at the battle of Kalka in 1223, was from Besud clan of Tayichiud.
Baiju, the commander of the Tammachi in Persia, was also from the Besud clan of the Tayichud. Chilaun, the one of Genghis Khan's four close companions, was from the Suldus, the sub-clan of the Tayichiud. His descendant Chupan reached the peak of his career during the reign of Ilkhan Abu Said and was given the title of chief commander of all Mongol Khanates by the court of Yuan Dynasty in 1327. In Chagatai Khanate, another aristocrat Buyan Suldus overthrew Qara'unas in Transoxiana in 1359 but was executed by Chagatai Khan Tughluq Temur in 1362.
People with clan name the Tayichud or the Taichud are found among the Mongolians in Mongolia and Inner Mongolia.