Trade Nodes are a gameplay mechanic in the Total War series. They are integral to trade.
Trade nodes operate similarly In every Total War game they appear in. They appear as yellow or golden circles with anchors within them, appearing on set points in seas on the world map. Trade ships placed within them generates trade goods, and as long as the controlling faction has a trade port that is not blockaded, this results in increased trade income. While any ship can occupy a trade node, only trade ships can generate trade goods. Trade nodes cannot be occupied by more than one faction.
Empire: Total War[]
In Empire: Total War, trade nodes appear in the four trade theatres. They are a significant distance away from all factions, and Pirates often patrol the waters, attacking all factions' ships indiscriminately. However, factions that manage to secure these trade theatres can stand to earn a tremendous amount of money.
Some factions (Great Britain, France, Spain and the United Provinces) have greater naval power than others, allowing them to better take advantage of trade nodes initially.
Napoleon: Total War[]
In Napoleon: Total War, the world map is restricted to just Europe and the surrounding waters, and trade nodes dot the edge of the map. This makes them much more accessible to all factions than in Empire: Total War, though some facions (namely Great Britain, France, and Spain) still have an advantage in this regard due to their starting navies, proximity to trade nodes, and access to more trading ports.
Four trade nodes lie in the north-west corner of the world map, with a British merchant fleet initially present; one is located in the western side of the map, just to the south-west of Ireland, and controlled initially by a small Spanish fleet. The bulk of trade nodes line the south-west to south of the world map, however, with five in the south-west corner (and one Batavian fleet, one Portuguese fleet, and one Spanish fleet occupying the nodes initially), and another five lining the African coast from the south-east of Spain to the south of Sicily. Finally, two trade nodes lie in the south-east corner of the map (south of Asia Minor), with one of the nodes being controlled by the Ottoman Empire, and two nodes on the eastern shore of the Black Sea, again with the Ottoman Empire controlling one node.
The Peninsular Campaign[]
Trade nodes return in The Peninsular Campaign, with five dotting the corners of the map. As the regions of the map are initially very poor, trade from these nodes can constitute a significant proportion of income for any faction.
Total War: Shogun 2[]
Trade nodes return in Total War: Shogun 2, operating in a near-identical fashion to previous iterations. One lies in the north-eastern corner of the map, and one in the north leaning slightly west, but the majority of trade nodes, four in total, lie on the west side of the map, off the coast of Kyushu. This gives Kyushu factions, such as the Shimazu Clan and Otomo Clan, a significant advantage over other clans in terms of potential trade profit. To a lesser extent, the Chosokabe Clan, Mori Clan, and Date Clan can also benefit from trade nodes, but the rest of the factions likely need to build up significant naval power before they can wrest control of the trade nodes.
Unlike Empire and Napoleon, trade resources aren't used for purely monetary worth and also fulfill requirements to construct certain buildings. For more information, see Trade#Total War: Shogun 2.