The brass vessel is a large, brass container that was cast into the central cistern in Iram of the Pillars by King Solomon, supposedly because it contained the tormented spirits of the Djinn. It tainted the water supply of the entire city, causing anyone who drank it to hallucinate their worst fears, which resulted in people appearing to be possessed by Djinn demons. The people were driven mad and the city was subsequently abandoned.
It was first sought by Queen Elizabeth, who intended to use the vessel's power to control anyone who opposed her through fear. She dispatched Sir Francis Drake to retrieve the vessel, though Sir Francis Drake abandoned his mission after quickly discovering the vessel's true nature and purpose, then hiding all traces of his voyage and mission, rewriting history in the process.
Centuries later, Katherine Marlowe, a member of a Hermetic Order with her right-hand man Talbot sought out the vessel with the same aim as Queen Elizabeth of controlling their enemies through fear. However, Nathan Drake and Victor Sullivan managed to destroy the winch raising the vessel by destroying it with a flare gun, allowing it to sinking down into the depths of Iram, and thus foiling Marlowe's plan, which the destruction of the winch also led to the collapse and destruction of Iram as well.