Shimun X (Syriac: ܫܡܥܘܢ / Shemʿon, died c. 1638) was Patriarch of the Shemʿon line of primates of the Church of the East, from c. 1600 to c. 1638. He is claimed both by the Chaldean Catholic Church and the Assyrian Church of the East. Upon accession to the patriarchal throne, he moved his seat from Urmia to Salmas, and also resided in Khananis near Qodshanis. He succeeded Patriarch Shimun IX Dinkha who was in full communion with the Catholic Church. Unlike his predecessor, who was officially recognized by Rome as the Patriarch of the Chaldeans, Shimun X was not formally recognized by the Catholic Church because his election was based on hereditary principle, reintroduced after the death of his predecessor. Hereditary succession was considered an unacceptable practice by the Rome. In 1616,