In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Silian like this:
SILIAN, a parish in Lampeter district, Cardigan; 2¼ miles N by W of Lampeter r. station. Post town, Lampeter, under Carmarthen. Acres, 2,182. Real property, £980. Pop., 341. Houses, 73. The property is divided among a few. The living is a p. curacy, annexed to Llanwnnen. The church is old but good.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Silian has changed, please see our redistricted information for the modern district of Ceredigion. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Silian and units named after it.
GB Historical GIS / University of Portsmouth, History of Silian, in Ceredigion and Cardiganshire | Map and description, A Vision of Britain through Time.
Date accessed: 05th December 2013
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Silian".