By the end of 19th century, the Assyrian Church of the East consolidated itself as the sole representative of all traditionalist Assyrians. It also managed to secure a certain level of autonomy within the highly complex system of Ottoman local governance in the bordering regions. On several occasions, Assyrian patriarchs refused to enter communion with the Catholic Church or merge with the Chaldean Catholic Church. On the other hand, by the end of 19th century some of its communities were converted to Protestantism by various western missionaries, while other communities were drawn to Eastern Orthodoxy. That movement was led by Assyrian bishop Mar Yonan of Supurghan in the region of Urmia, who converted to Eastern Orthodoxy in 1898, through the Russian Ecclesiastical Mission in Urmia. Activities of foreign missions among Assyrians represented not only a religious, but also a political challenge, since the Ottoman authorities were very suspicious of any foreign presence among their Christian subjects.