Focusing on the time periods after the invention of gunpowder. It will deliver 12 unique and challenging scenarios created by the development team at Firaxis as well as some esteemed members of the Civ Community. Civ IV: Beyond the Sword will also include ten new civilizations, sixteen new leaders, five new wonders, and a variety of new units that will offer even more fun and exciting ways for players to expand their civilization's power as they strive for world domination.
in this mod you can play as a new nation called the assassins and new unique units for the assassins nation plus brand new techs
run the exe file and extract all of the files to the civ4 mods area