Jonril: Gateway to the Sunken Lands is a fully populated, predominantly human city designed to be used with the Midkemian Game System, The Tome of Midkemia. It is also compatible with most of the currently available fantasy role player games, and, with some modification, with some science-fiction role playing games and modern military role playing games.

Jonril is a truly cosmopolitan city, drawing people from many parts of Triagia (the largest continent upon Midkemia). From as far distant as the King's city of Rillanon and the heart of the Empire of Kesh come traders and adventurers seeking riches from the Sunken Lands. This accounts for the high number of foreigners residing in Jonril.

Jonril is a city with little internal constraints upon business, or tariffs upon trade, though some drugs are contraband. The small import/export duty and the few contraband goods means smuggling in Jonril is done on a small scale.