Tributing is the mechanic used for sending resources to ally players.
Gameplay[]
To give/tribute resources to another player, look at your resource counter at the top of the screen and click on the numerical resource count. This will take you to the Tribute Panel which will let you send resources to your specified party. You can also access the tribute bar in the balance icon while selecting the Market.
Without upgrades, the Tribute Ratio is 2:1 (from the sender to the receiver).
Upgrades[]
Technology upgrades are available through the Market to improve the trade ratio.
Trade Routes - Reduces Market penalty.
Shipping Lanes - Reduces Market penalty.
Please note that the two upgrades will reduce the market penalty to 25% not 0%. As 50%(Shipping Lanes) of 50%(Tribute penalty) is 25%.