The Quinta District is the western district of Wall Maria that appears in the light novels Attack on Titan: The Harsh Mistress of the City, Part 1 and Attack on Titan: The Harsh Mistress of the City, Part 2.
Story: In the year 845, shortly after the fall of Shiganshina District, citizens of Quinta were evacuated to Wall Rose but were overwhelmed by Titans before the evacuation could be completed. As a result, around half of the district's population was left behind. Neither government officials nor high-ranking officers of the Military remained in the city after the district became isolated, and authority over the city fell to a Garrison soldier name Rita Iglehaut.
Trivia: "Quinta" is a Portuguese word whose general meaning is "a house on the outskirts of the town, or in the country," possibly referencing the position of the eponymous district on the outermost of the Walls.
Source: Quinta District, available under CC BY-SA 3.0.