From RocksfallWiki

Sarcha is the largest city left in the world, due constant wall expansion by the Sarchans and Tunnel Runners. Unlike other cities, which expand the walls outward all at once, the Sarchans have taken a different approach, expanding either the east or west side of the city. This is mainly due to respect for their ancestors, as an old burial site lies to the north, and there is a strong superstition against building on the other side of the river to the south.

Each section of the city from these expansions has its own view of how their part of the city should be run. Many areas have come under the control of gangs and minor league warlords. Others have developed a lawful and civilized outlook. This has had little effect on the Sarchans themselves, who have claimed the most inner area and out areas for themselves. They see these internal conflicts as breeding stronger people to defend the wall. They do require that each section to supply a number of fit people during the attacks on the wall and that no inner conflict in the city can present while the defense of the wall is being carried out. Much of this is due to careful planning of some of the nobility that have helped maintain order in the city, though they have many headaches and sleepless nights trying to figure out which group can operate which section of the walls…

Sarcha's defensive walls are unique, in that they have a ledge on both the ground and on the top of the wall so that the Sarchans can fight the Green at ground level without stepping upon it. There have been no recent expansions in Sarcha due to the lack of manpower to defend another push. This lack of manpower has also lead to longer shifts on the wall for the Sarchans.