Tsono-Xuhil is the mad Hist of Mazzatun, kin to the Xit-Xaht tribe. Tsono-Xuhil resides atop the pinnacle of Mazzatun, known in layman's terms as The Mad Hist's Summit. Here, Tsono-Xuhil presides over Mazzatun, its shadow looming over the entire city. Its sprawling roots stretch out over the xanmeer and the surrounding cliffs, arching over countless eggs nestled in a communal uxith. The uxith extends around the tree outside the walls of the xanmeer, and rests on several cliffs shaded by the roots. A mysterious substance known as amber plasm seeps from its bark and drips to the earth below.
Tsono-Xuhil was obsessed with returning Black Marsh to the pre-Duskfall way of life, and advised its tree-minder, Na-Kesh, in her attempt to manipulate its strange sap to empower the Xit-Xaht. Ingesting or immersing oneself in amber plasm has devastating side effects, most notably madness. The Tree-Minder made use of the amber plasm in accordance with the will of her Hist. She was able to strengthen herself, and transform many of the Xit-Xaht into powerful soldiers. The Hist and its tree-minder were not keen on Sithis, for he represented Change. Tsono-Xuhil despised Change, and sought order in the city of Mazzatun. The Hist and its Tree-Minder viewed the new Argonian way of life as savage and low. Those who follow Sithis and acknowledge that he is Change now "live in mud huts and eat old fish from wooden bowls"; Na-Kesh and her Hist believed that their people were above such things.
Tsono-Xuhil sought to have a shining city of stone built to house its children—one that would rival even the glory of the Imperial City. To this end, the Hist called to its people, instructing them to build a winding stone xanmeer upon the ruins of old Mazzatun. The Hist allowed them to bring in slaves to assist them in the endeavor. The Hist even created a mighty Argonian Behemoth for the purpose of subjugating Saxhleel from other tribes to build the majestic city nestled in its roots. The Hist's madness seeped into the Xit-Xaht tribe, and even the very soil its roots dug into. For ages, Argonians from other tribes knew to stay away from Mazzatun and its mad Hist, for they could feel that something was wrong with the city on a primal, organic level.
In 2E 582, the Xit-Xaht tribe's raiding was put to an end by the Undaunted at the behest of a Su-Zahleel tribesman. The Xit-Xaht had raided the Su-Zahleel's village and enslaved its inhabitants, and the Argonian asked the Undaunted to free his tribe from the Xit-Xaht's clutches. The efforts of the adventurers managed to save at least one of the tribe's elders from an agonizing death involving being drenched in amber plasm. After Tree-Minder Na-Kesh's demise, the mad Hist was delivered into deep slumber by the surviving Su-Zahleel elders, who hoped to alleviate the tree of its psychosis.
- Appearance of Tsono-Xuhil in ESO
- Appearance of Amber Plasm within Ruins of Mazzatun in ESO
- Na-Kesh's Journal — Tree-Minder Na-Kesh
- Appearance of Xit-Xaht Sludge-Slingers in ESO
- The ability of Xit-Xaht tribesmen to become empowered by amber plasm in ESO
- Events of Sap and Stone in ESO
- Appearance of Xal-Nur the Slaver in ESO
- Captive's Journal
- Loading Screen text from the Ruins of Mazzatun in ESO