Thomas Barclay was a missionary of the Presbyterian Church of England to Formosa from 1875 until his death. His ministry in southern Taiwan has been compared to the work done in northern Taiwan by George Leslie Mackay. He founded Tainan Theological College and Seminary in 1876.

Pe̍h-ōe-jī, sometimes known as Church Romanization, is an orthography used to write variants of Hokkien Southern Min, particularly Taiwanese and Amoy Hokkien, and it is widely employed as one of the writing systems for Southern Min. During its peak, it had hundreds of thousands of readers.