The Syriac Gazetteer is a geographical reference work of Syriaca.org for places relevant to Syriac studies. “Places relevant to Syriac Studies” include places named in Syriac texts (such as Ḥarqel — ܚܪܩܠ), places interesting to historians who work on Syriac texts (such as Dura-Europos), and places where scholarship on Syriac is being produced (such as Japan). There are no temporal or spatial boundaries for the geographic database, which collects places relevant to any period of history useful for Syriac studies, from places mentioned in the Peshitta version of Genesis to places founded recently, and from ancient Edessa to Mongol-era outposts in China and diaspora communities in the United States of America. At least in theory, any type or size of place could be represented in the geographic database, from large empires to single churches or a particular named city gate. Maps are provided for places whose location is known, but the database includes places which are not located or even locatable: each place is a conceptual thing with a mental existence related to, but not reducible to, its physical manifestation. Mythological and other ahistorical places are also included in the database.
And see AWOL's Roundup of Resources on Ancient Geography