Q: Who established Sayyid dynasty?  

The dynasty was established by Sayyid Khizr Khan, deputised by Timur to be the governor of Multan (Punjab). Khizr Khan took Delhi from Daulat Khan Lodi on May 28, 1414 and founded the Sayyid dynasty. But he did not take up the title of sultan and nominally, continued to be a Rayat-i-Ala (vassal) of the Timurids, initially of Timur and after his death, his successor Shah Rukh, grandson of Timur. Khizer Khan was succeeded by his son Sayyid Mubarak Shah after his death on May 20, 1421, who styled himself as Muizz-ud-Din Mubarak Shah in his coins. A detailed account of his reign is available in the Tarikh-i-Mubarak Shahi written by Yahya-bin-Ahmad Sirhindi. After the death of Mubarak Shah, his nephew, Muhammad Shah ascended the throne and styled himself as Sultan Muhammad Shah. Just before his death, he called his son Sayyid Ala-ud-Din Shah from Badaun and nominated him as his successor.