Russian Empire). Each civilization has unique shipments to aid its cultural, economy and military (for example, the Ottomans are able to order a shipment of gold for both them and their teammates). There are other civilizations playable via the campaign, which include The Knights of St. John, John Black's Mercenaries, and the United States of America, which are played as the Spanish, German and British civilizations, respectively, with slight modifications. Non-playable campaign civilizations include the Pirates, Circle of Ossus and Native Americans, although these civilizations are playable using the Scenario Editor. Twelve different tribes of Native Americans are in the game as well, but these are not in themselves playable factions. However, players can gain access to unique units and improvements by forming an alliance with the tribes by building a trading post at their camps. The native tribes featured are the Aztec, Carib, Cherokee, Comanche, Cree, Inca, Iroquois, Lakota, Maya, Nootka, Seminole, and Tupi. Three of these tribes were made playable in the expansion pack Age of Empires III: The WarChiefs: the Iroquois, Lakota (under the name Sioux) and Aztecs. These civilizations were removed as the smaller, alliance based tribes and were replaced by the Huron, Cheyenne, and Zapotec, respectively. In The Asian Dynasties another three civilizations were added, along with several new native tribes. The civilizations are the Indian, the Japanese, and the Chinese. Home Cities Age of Empires III is the first game in the series to introduce the "Home City" concept. The Home City functions as a second city, a powerhouse that is separated from the active game. It cannot be attacked or destroyed, although an Imperial Age upgrade called "Blockade" stops the player's opponents from receiving Home City shipments. Similar to a role-playing game character, the Home City is persistent between games, meaning that upgrades gained through separate games can be applied and stay applied for as long as that particular city exists. Multiple Home Cities can be created and maintained, although each supports only one civilization. The Home City is composed of five main buildings from which the player chooses their new shipment cards and customizations: The New World Trading Company, the Military Academy, the Cathedral, the Manufacturing Plant and the Harbor. Players can also access the Home City during a match by clicking on the "Home City" button represented on the HUD as the nation's flag. The Home City functions differently inside a