In the Year 333 of the Great Nation of Dhuþchia...

The very wise and clever Dhuþchian people have always known that the coastlines and riverbeds are great places to live, because there's lots of fish and other seafood to eat. Sure, people can subsist on agriculture, forage, and hunting, but agriculture is a lot of tedious toiling, and forage and hunting are both quite chance-based. Fishing, on the other hand, has the reliability of farming and the labour of trapping – just throw up some seine nets and fishing weirs on the rivers and tidal coasts and you'll just get free food delivered straight to you. If you want more, a leisurely cruise on your boat with a net or line is all you need.

Given these factors, it's no surprise that as the cities, reliant on backbreaking agriculture, grew larger and smellier, the people moved to the coastlines and riverbeds in droves.

Effect: Glorious Dhuþchia expands to the highlighted tiles.