Trade

Trade is a means to generate gold in Age of Empires, Age of Empires II, and Age of Mythology.

Overview
In order to trade and generate gold, caravan/trade-type units must traverse between two Docks, two Markets, or a Market and a Town Center. The greater the distance between the two structures, the greater the amount of gold provided.

Due to its importance, especially in later stages of the game where other gold sources are used up, trade routes are a primary target for attacks. Therefore, it is recommended to guard them against attacks.

Age of Empires
In Age of Empires, trade is only possible between Docks, with Trade Boats or Merchant Ships. Note that, unlike in later games, trade costs resources.

Age of Empires II
In Age of Empires II, trade is possible between Markets with Trade Carts, or between Docks with a Trade Cogs. Players can also trade with enemies' or neutral players' structures, but they risk sacrificing their trade units to an attack, thus emulating the real life practice of smuggling. Note that unfriendly structures can still be used for trading even the owner of said structure has resigned. Therefore, in games without teams or with no teammates left, it is wise to not raze Markets or Docks of resigned players.

Age of Mythology
In Age of Mythology, trade is conducted between a Market and a Town Center, with one of the following units, depending on the player's civilization:
 * Donkey Caravan (Greeks)
 * Camel Caravan (Egyptians)
 * Ox Caravan (Norse)
 * Llama Caravan (Atlanteans)
 * Yak Caravan (Chinese)

Age of Empires III
In Age of Empires III, the concept of trading has changed dramatically. The game adopts Trade Routes which are very different from the trade known in former games of the series.