Civilizations can no longer trade with technology, as in previous versions of the game, instead civilizations can carry out common technological enterprises. Two civilizations at peace can form a research agreement that requires an initial investment of gold and provides the two civilizations with a certain amount of science as long as they remain at peace.  Before the PC 220.127.116.112 version of the game, civilizations were equipped with unknown technology after a series of twists and turns of uninterrupted peaceful relations. It is possible for a civilization to sign a research agreement just to get an enemy to spend money that could be used for other purposes; AI civilizations are programmed to sometimes use this tactic before declaring war.  British actor W. Morgan Sheppard delivers the story for the opening films of the original game and its expansion packs, quotes on the discovery of new technologies and the construction of tourist sites and the introduction of the player`s chosen civilization at the beginning of each new game.  Declarations of war lead to the breakdown of trade routesIf one nation declares war on another, all trade routes between them are cut off and units are lost. There is no gold gain, and you have to rebuild it. It is better to plunder the trade routes between the Civ as you DoW as the act that begins the war, allowing you to win some gold from the action. Of course, contemporary commerce is much more complex in the real world and is often done without anyone leaving its place, thanks to technology.
Financial transactions, for example, are done entirely by computer… But we will not talk about such complex problems here. In the game, trade is essential to maintaining the gold income of your empire and to the happiness of your subjects. It is also a way to preserve the vital strategic resources that your countries lack, etc. Overall, you will lose the game if you do not know how to act, both in setting up trade routes and in negotiating trade agreements with other nations. The last and most complex type of trading is trading agreements that you place with other nations. This is done without preconditions (you don`t need to create a network) although you will of course have to be at peace with your business partner. The creation of trade agreements is the result of diplomatic negotiations initiated either by yourself or by your partner, during which the two parties agree on the exchange of goods or for a certain amount of 30 rounds. In the real world, this type of negotiation is one of the most frequent topics of diplomatic discussion, although there are usually agreements that establish general rules for trade, not direct trade in goods. On March 15, 2013, an expansion package entitled Brave New World was announced and released on July 9, 2013 in North America and July 12 internationally.   The extension has added new features to the basic game, as international trade routes, world congress, tourism, great works, two new scenarios, eight new miracles, several new units and nine new civilizations: Assyria (led by Ashurbanipal), Brazil (led by Pedro II), Indonesia (led by Gajah Mada), Morocco (led by Ahmad al-Mansour), Poland (led by Casimir), Portugal (led by Maria I) , the Shoshone (directed by Pocatello) Venice (directed by Enrico Dandolo) and the Zulu (directed by Shaka).
In addition, Ethiopia, which until now was available in the first enlargement package, is included in the enlargement.  This is a new type of business, introduced in Brave New World. It consists of a joint government enterprise, where the government provides a business unit and infrastructure to private merchants, who then use it to trade with government-designated destination cities.