Yu Dao is a Fire colony in the western Earth Kingdom that has existed since 37 BG. Mixed streets, mixed families, a generation of children who can speak both languages and are trusted by neither court automatically. Roku forbade further expansion after the crisis that created the colonies. Roku is dead. In the same week official mourning banners go up in the Capital, a border "incident" can be scheduled here. This is the powder keg of the first year.
WHO STANDS WHERE
Governor Ryozen works the upper terrace of the Governor's Residence. He wants the colony permanent and profitable. He has Mandate correspondence about "future military use." He is not a mustache-twirling villain every hour of the day; he is a man who thinks the earth under the smelters already belongs to the future.
Master Bohai bakes in the Brick Lotus bakery basement in the Old Earth Quarter. His resistance wants to keep Earth identity without getting the street burned. He will deal with Omashu or the White Lotus, not the Dai Li if he can help it. A grain-store list in the basement is colonial logistics and resistance gold.
Ferryman Wudao works the public ferry slip and can stall a patrol. That stall is sometimes worth more than a fight in the marketplace.
Dock worker Sarn works the smelter quay. His sister was "reassigned" to a locked warehouse. He is a hook, a guide, and a reason not to treat the harbor as scenery.
The mixed marketplace is where colonial mixed-heritage PCs sound like locals. Fire flakes and earth dumplings share a lane. A new ordinance can close a stall overnight.
WHAT "EXPANSION RESUMES" LOOKS LIKE
Not always an army pouring over a ridge on day one. It looks like tighter ordinances, more Fire officers on the terrace, foundry shifts that run longer, a warehouse that no longer lists its contents, a ferry that is "inspected" until the wrong passenger gets off, a letter from the Ministry of Imperial Planning about security corridors. Years 6-9 on the clock make those corridors explicit. Year 1 is when the party can still stop a local spark from becoming a doctrine.
PLAYING BOTH SIDES
A Fire PC posted here as clerk, soldier, or settler can believe in "shared prosperity" and still notice Sarn's missing sister. An Earth PC in the bakery can refuse a riot that would burn their neighbors. A mixed-heritage PC can walk into both rooms and be asked to choose too soon. Queen Meishou will use Yu Dao to embarrass Yuanli. Yuanli will call it an outer matter. Sozin will call it a closed issue. Hesun will call it a future harbor.
OTHER COLONIES
Yu Dao is the named jewel and the playable streets. Other western holdings can be sketched as lesser towns, garrisons, and farms under the same legal shadow. Do not invent a canon-named later colony as if it already had its Hundred Year War reputation unless a source places it in this era. If you add a smaller colonial village, label the details original, give it a vendor and a problem, and tie it back to the same question: Roku said stop. Who, now, says go?