Page "Civilization IV" Paragraph 4

Diplomacy in Civilization generally involves the trading of goods.

Specific technologies are required to trade different commodities ( for instance, a civilization must possess the technology of paper to trade world maps ).

Players may trade technologies, resources, maps and gold.

Advanced diplomacy options include the creation of trade embargoes, the promise of military aid, and the adoption of particular civics and religions.

Finally, the United Nations wonder allows the passing of global resolutions ( such as the Nuclear Non-Proliferation Treaty ) in addition to granting access to the diplomatic victory.