Districts

The districts are expanded walled cities that are located on four sides of each wall. Since the wall extends further than 500km, there aren't enough garrison soldiers to guard it. The outer district's purpose is to attract the Titans and to keep them away from other locations of the wall. Living in the outermost wall (wall Maria) isn't just poor but also extremely dangerous since the world outside is fully dominated by Titans. According to the manga of "A Choice With No Regrets" every district within wall Sina has an underground town,which would make the total amount of districts within that wall 10.

According to that same manga, the underground is poorer and slightly more dangerous than wall Maria. Since it's several meters below the surface, most people die because of the lack of sunlight,others because of dehydration,deadly infections or murderers.

The districts in wall Rose aren't like the inner or outer districts. It's not deep underground or right next to Titan territory,but mostly a cold,peaceful region.That was until Shiganshina was breached by the Colossal Titan and Armored Titan.

The current status of the walls is caotic. After the fall of wall Maria, humanity was pushed into wall Rose. Soon after that, the Trost district was breached. Then the population of a small village named Ragako was overtaken by Titans. Afterwards the military took the royal capital,then a Titan twice the size of the colossal Titan appeared and caused major damages to the Orvud district. So far this is what has happened within the two walls that are left.