You will receive supplies by placing orders in production buildings
(also referred to as workshops). Unlike residential buildings, you need
to set these orders yourself. In addition to supplies from production
buildings, you will receive supplies every now and then as a reward for
successfully completed quests, conquered territories or plundering
buildings. You need supplies, just like coins, to build, to recruit
units and to unlock technologies.
Supplies packages are sometimes awarded during events. The amount of supplies included in every package differs with age.