Sid Meier's Civilization IV: Warlords

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

Sid Meier's Civilization IV: Warlords is the first expansion pack for the award-winning game that has become an instant world-wide hit. Paying homage to some of history's greatest military leaders, the expansion delivers six unique and interesting scenarios, giving players the chance to change the course of history with the help of their new powerful "warlord" unit. Civ IV: Warlords includes new civilizations, leaders, units, and wonders that offer even more fun and exciting ways for players to expand their civilization's military power as they strive for world domination.

Warlords: a new great person type called the Warlord.
Vassal states: conquer an enemy and subjugate them to your rule.
Game scenarios: the expansion delivers eight scenarios.
New civilizations: the pack provides six new civilizations and associated unique units.
Civilization leaders: 10 new leaders, including leaders for the new civilizations as well as additional leaders for existing civilizations.
Leader traits: two new leader traits.
New wonders: three new wonders.
Unique buildings: each civilization has a new unique building as well as their unique unit.
New units, resources, and improvements: many new items are presented throughout the scenarios.
Core game tweaks and additions: expanded features and gameplay tweaks made to the core game.
Post-release patches and game upgrades: the pack contains all of the patches and game additions (pit boss, etc.) yet released for Sid Meier's Civilization IV.