Venture Though Tamriel
Black Marsh is a dense swampland region of southeastern Tamriel, home to the reptilian humanoid race of Argonians and a race of sentient trees known as the Hist. Mer races also use the name Argonia, a reference to an obscure ancient battlefield, to avoid the negative connotations of the term “Black Marsh”. Argonians thrive in the foreboding swamps of Black Marsh, a lush and threatening land teeming with poisonous plants and violent predators. The region’s tropical climate lends its plants the capacity to overturn all attempts to cultivate them. Foreign agricultural, colonial, and commercial ventures beyond the slave-trade have met with abject failure. The native Argonians organize themselves on the tribal level with success and efficiency, and were only loosely integrated into the ruling Empire.
The earliest inhabitants of the Black Marsh and its environs are believed to have been the Hist, great life-giving trees of unknown capacities. The region presently known as Black Marsh was once part of a much greater landmass within the domain of the Hist, but the greater part of the region was flooded during the wanderings of the humanoid Mer races. “The Hist were bystanders in the Ehlnofey war, but most of their realm was destroyed as the war passed over it. A small corner of it survived to become Black Marsh in Tamriel, but most of their realm was sunk beneath the sea.” Argonians came to inhabit Tamriel in small, preliterate communities by the Early Merethic Era.
Canonical information regarding the period in-between the mythic origins of Black Marsh and the rest of the Third Era is sparse. The novellas 2920, The Last Year of the First Era and The Wolf Queen state respectively that the major Black Marsh city of Soulrest had an Argonian battle-chief by 1E 2920, and that Lilmoth had an Argonian priest-king by the first century of the Third Era.
In 1E 2811, Argonian armies from Black Marsh came into conflict with the neighboring Cyrodilic Imperials. The last of these Argonian armies was defeated by a Cyrodilic force. A possible contradiction ensues with an earlier account from Morrowind, which states that “No army of Morrowind or Black Marsh has ever threatened the security of any other Imperial province, let alone the security of Cyrodiil itself,” but this particular passage could be explained in any number of ways, particularly given that the book in question–The Eastern Provinces Impartially Considered—is generally polemical.
Black Marsh was eventually incorporated within the Second Cyrodilic Empire in 1E 2837. Though it is not directly indicated in any in-game lore, a passage in the book A Short History of Morrowind implies that Black Marsh was incorporated into the Empire by treaty or pact rather than by military dominion. “Resdayn was the last of the provinces to submit to Tiber Septim; like Black Marsh, it was never successfully invaded, and was peacefully incorporated by treaty into the Empire as the Province of Morrowind.” Imperial domination changed little of the tribal organization of Black Marsh’s society, but wrought disastrous changes to its economy as the small farms of Argonian peasants were replaced with massive cash-crop farms and traditional forms of transportation were usurped by foreign methods unsuited to the native terrain. These changes were eventually remedied as the land’s administration chose to return to previous methods of business. There have been some small attempts to convert the residents of Black Marsh to the Cyrodilic pantheon of the Nine Divines, but most have been unsuccessful.
During the later years of the Third Era, Black Marsh came into conflict with its Dunmer neighbors to the north in the bloody Arnesian War. The armies of Black Marsh were destroyed, but an Argonian was able to capture and murder an influential Dunmer merchant named Roris, who was later made a saint by the Dunmeri Temple. Interestingly, documents prepared for Lord Vivec by the Tribunal Temple imply that Black Marsh retains control of some historically Dunmer provinces, despite the Dunmer victory in the Arnesian War. In detailing Dagoth Ur’s plans, the Temple states that he wishes to “Recover ancient territories stolen by Skyrim and Argonia”. The Dunmer and the Argonian races, perhaps unsurprisingly, have a “long standing and bitter hatred for one another”.
After the Oblivion Crisis and the beginning of the Fourth Era, Black Marsh seceded from the Empire along with Elsweyr. Morrowind was substantially weakened when the Ministry of Truth became unstable and crashed into Vvardenfell, destroying much of the island. The Argonians of Black Marsh invaded and conquered the crippled Dunmer. In 4E 40, a floating, soul-fueled city known as Umbriel moved over the city of Lilmoth after being summoned through Black Marsh by the An-Xileel and a rogue Hist tree, destroying and killing all foreign entities and ‘assimilated’ Argonians.