Zaya Pandita was from the Khoshuud group of the Oyirad. He became a Tibetan Buddhist in 1615. He practiced asceticism in Tibet and returned to Oyirad in 1639. He taught Tibetan Buddhism to the Oyirad and Mongols (Khalkha). In 1645 he was invited to Kalmykia.
In 1648 he developed the Todo script (todo üzüg, from todorkhoi (clear)) by improving the traditional Mongolian script. He eliminated all ambiguities of the traditional script and adjusted it to the Oyirad dialect. The Todo script is still used in Xinjiang with slight revisions, but is not taught in education due to China's policy.