I recall something about a 6th-century Christain monk (Nestor) who travelled to Asia. This man founded several communities, which became a sect of Christianity. Are there any of these communities left? What are their beliefs?
The Assyrian church is still around and the Chaldean Catholic church also derives from the “Nestorian” tradition in the Near East. For more info I’ll just direct you to a Wikipedia article, which I would otherwise plagiarize :).