Marley is a nation located beyond the Walls and across the ocean from Paradis Island. Marley was once conquered by Eldia in ancient times, but during the Great Titan War, the Marleyans rose up and subjugated all of Eldia's territory with the exception of Paradis Island. Marley sustained its global power using the power of the Titans possessed by the Warrior Unit, but began to lose its status due to lagging behind other nations in technological progress.
Marley serves as the main antagonist to the Eldians inside the Walls and filled Paradis Island with Titans to keep them inside. In year 854, Marley officially declared war on Paradis Island.
History: Marley was a powerful nation in ancient times; however, around 2,000 years ago, a slave of the Eldians named Ymir gained the power of the Titans. King Fritz used her abilities to defeat Marley and force their surrender. One of the Marleyans attempted to assassinate Fritz several years after their defeat, but Ymir intervened and was killed instead.
Story: After Marley's failed operation, the Mid-East Union, a coalition of various nations, took advantage of the defeat and declared war on the nation, starting a four-year long war. A significant portion of the war took place on the sea, with Marley gaining the upper hand over the course of the four years, at the cost of half of its navy. During the last battle of the war, the Marleyan forces, with the help of its infamous Warrior Unit, was able to conquer Fort Slava and destroy the Mid-Eastern fleet.
Trivia: The emblem of Marley appears to be a seashell motif and is found on several structures located in Liberio as well as official military paperwork. The shell has seven sections, which coincidentally is the number of Titans Marley gained during the Great Titan War. Marley draws on Latin and Italian inspiration for much of its naming and culture.
Source: Marley, available under CC BY-SA 3.0.