|Time period:||2807 – 2868|
|Capital world:||was Shadow??|
|Military:||Clan Mongoose Touman|
|Secret Service:||Clan Mongoose Watch|
The Clan Mongoose home planet of Shadow was also where the clan's totem-animal originated. Adopted from the animal that killed the dangerous venom worms, which were a great threat to humans, and as such endeared the mongoose to the Clan. Clan Mongoose was Absorbed by Clan Smoke Jaguar in 2868.
After the annihilation of Clan Wolverine, Khan Loris of Clan Mongoose attempted to exert control over Clan Snow Raven, which had been badly wounded by the Wolverines. Loris withdrew his attempts at Absorption when the Snow Raven Khan Stephen McKenna threatened to give the Grand Council tapes proving a personal connection between Khan Loris and Khan Sarah McEvedy of the Wolverines. Clan Mongoose also struck ruthlessly at Clan Blood Spirit, often disregarding Clan rules of engagement.
In 2844, motivated by jealousy, the Mongoose warriors struck at Clan Star Adder and ruthlessly massacred the Adder colonists on Marshall. The outraged Star Adders took their revenge by wiping out the entire Mongoose attack force. In retaliation, the same Star Adder commander moved and conquered the Mongoose colony on Tokasha. 
During the early years of the Golden Century, many conflicts would arise as the Clans expanded to fill up the volume of the Kerensky Cluster. Clans that used their resources for exploration and colonizing often had to defend their investments from another Clan that was waiting to poach the fruits of their labor with military strength. Surprisingly, the most aggressive Clan of this era was not the Smoke Jaguars, despite being well-known for their casual brutality. That distinction belonged to Clan Mongoose. Driven by Khans who mortally feared showing any martial weakness to their competitors, they were almost as infamous for their incessant attacks on many of their neighbors as they were for their constant political maneuvering, which had over the years earned for their Clan the nickname "the Weasels".
In 2868, the Mongooses geared up for a strike against the Smoke Jaguars on the colony world of Atreus as part of an ongoing feud with that Clan. Just as they launched this attack, the Star Adders launched their own multi-world assault on Clan Mongoose in revenge for the loss of nearly half their colony worlds five years earlier. Colony after colony fell to the well-executed plans of the Star Adders and their Khan.
The disrupted Mongoose attack against the Smoke Jaguars on Atreus was soundly defeated. This turn of events would lead Khan Walter Martindale of Clan Mongoose to hastily bring charges against Clan Smoke Jaguar in the Grand Council, accusing them of starting a wasteful conflict. While this was a blatantly obvious ploy to stall for time in which to get his Clan out of the pit it had dug for itself, what decided his fate - as well as the fate of every other Mongoose citizen - was his shameless use of the Great Kerensky's words in an attempt to bolster his position. Infuriated by this sickening display of political maneuver, Smoke Jaguar Khan Theodore Osis would declare the Mongoose leaders incapable of ruling their citizens. Calling Khan Martindale's citation of the Great Kerensky's words in a ploy to cover his Clan's weakness an act of Treason against the Grand Council, Khan Osis would immediately demand a Trial of Absorption against their Clan. The Grand Council had seen far too many political stunts by the Mongoose Khans during the past few decades, and voted in favor of the Smoke Jaguar Khan's motion. Clan Mongoose would have little time to prepare their already damaged Touman for the onslaught ahead.
Though they fought bravely, and made Clan Smoke Jaguar pay a stiff price for their victory, battle by battle the Mongoose touman and remaining colonies were destroyed.
All Mongoose assets became the property of the Smoke Jaguars, greatly enriching them. The Grand Council would even allow them to trade land to certain Clans for the right to take an unspecified amount of WarShips (but not many) from naval caches in order to recoup losses to their shattered fleet. But Khan Osis would cast aside the genetic legacies of all Mongoose warriors, boasting that his Clan "will never use the tainted genes of these schemers", desiring that the vanquished Clan fade away. Later, the Cloud Cobras led by a bold Khan Josef Mannix would bid for and win the rights to over 70 legacies from 11 different Bloodnames, mostly aerospace pilot legacies. The Smoke Jaguars would be angry over the Cloud Cobra's decision to activate these lines, but there was little they could do to defend legacies that they had scorned.
By 3067, a single WarShip of the Clan remained in mothballs in the Clan Capital system of Strana Mechty. The ancient Du Shi Wang-class Battleship, the Quicksilver Mongoose, had faithfully served the Clan until the Clan's ultimate demise. 
The aggressiveness and bloodthirstiness of Clan Mongoose gave this Clan few true allies and only real enemies. Their use of political maneuverings and manipulation of Kerensky's words to excuse their actions has also not bore them any fruitful relations.
|Clan Blood Spirit||Enemy||The Blood Spirits had a long-standing feud with Clan Burrock. Clan Mongoose was allied with the Burrocks, and became caught up in this enmity.|
|Clan Burrock||Ally||The Mongooses were known to ally with Clan Burrock in the latter's feud with the Blood Spirits.|
|Clan Star Adder||Enemy||The massacre of Star Adder civilians at the hands of the Mongoose Touman on Marshall would earn that clan's contempt. In response the Mongoose commander who committed the act would be beheaded and his corpse shown as an example stating, "This is our surkairede, to forget is impossible." The Mongoose civilians would later transplant the population on an Adder world as compensation.|
|Clan Smoke Jaguar||Enemy||This would be the enemy that would seal the fate of the Mongooses. After Clan Mongoose provoked the fury of Clan Smoke Jaguar, they were approved for Absorption, which was carried out by the Jaguars. The victorious Jaguars would absorb the Clan and their assets, but refused to take their genetics, allowing them to fade into obscurity.|
- Historical: Operation Klondike, p. 92, 93 - "A Legacy of Violence: The Jaguar pounces"
- Era Digest: Golden Century, p. 11, 12 - "Life as a Mongoose"
- Field Manual: Crusader Clans p. 112, 113 - "Into the Golden Century"
- Invading Clans, p. 49, 50 - "The Golden Century"
- Era Digest: Golden Century, p. 7, 8 - "Warriors above Politicians"
- Era Digest: Golden Century, p. 11, 12 - "Warriors Above politicians"
- Era Digest: Golden Century, p. 9 - "Warriors Above Politicians"
- Field Manual: Warden Clans, p. 21, 22 - "Maturation Amid the Renaissance"
- Technical Readout: 3075, p. 252, "Du Shi Wang" - former Capellan Battleship served Mongooses until their demise.
- Historical: Operation Klondike, p.123