An organization dealing in shady business and criminal activity.

Originally founded by a lich named Manshoon to spred his controll across the Moonsea.
From the outside Zhentarim appear as the finest mercenaries that gold can buy and use this as a cover to commit their illicit deeds.

From The Rise and Fall of The Black Network by Seraphine Wraithstalker

The initial formation of the Zhentarim is shrouded in mystery and shadow. In the earliest days of the organization, its leaders, notably the enigmatic Manshoon and the formidable priest Fzoul Chembryl, assembled a network that combined commerce, tyranny, and dark magic to grasp for power in the lands surrounding the Moonsea.

The book begins by exploring the organization’s genesis as a militant extension of the church of Bane, god of tyranny. It carefully outlines how the Zhentarim grew from a militant sect to a vast shadow network that influenced trade, politics, and even warfare in the heartlands of Faerun.

The author, Seraphine Wraithstalker, meticulously describes Manshoon’s ascent as a feared leader and an influential figure in the Zhentarim. She highlights the intricate plans he set into motion to extend the reach of the Black Network, interweaving stories from anonymous insiders, forgotten documents, and encrypted messages to piece together a detailed picture of the past.

Seraphine does not shy away from the darker aspects of Zhentarim history. The book chronicles a period of dramatic growth, marked by ruthless intimidation, brutal efficiency, and strategic alliances, which led to the Zhentarim dominating several key trade routes and infiltrating influential merchant guilds.

Wraithstalker paints a picture of the Zhentarim at their peak: a vast, shadowy organization able to manipulate events from behind the scenes. At the same time, the book sheds light on the internal strife and rivalries that threatened to tear the organization apart. Detailed accounts of betrayals and purges within the Zhentarim show the precarious balance the organization had to maintain.

The book then delves into the infamous Manshoon Wars, sparked by a failed attempt on Manshoon’s life. Wraithstalker lays out the horrifying details of the catastrophic conflict, which set dozens of Manshoon clones against each other in a battle for dominance. The war left much of the Zhentarim in disarray, causing a severe decline in their influence and power.

The author covers the power vacuum left by the wars and the rise of new leaders who tried to restore the Zhentarim to its former glory. She discusses the significant changes the organization underwent in adapting to a new era and the different challenges it faced.

Towards the end, Wraithstalker speculates on the current state of the Zhentarim, discussing potential threats and emerging figures of power. She leaves the readers with a sense of an organization that, while not as powerful as in its heyday, is far from extinguished and may be slowly regaining its former influence.