Events are random occurrences that can affect a civilization and happen at semi-random times. The two events that can currently occur are being attacked by enemies or having the trader visit.
Attacks are scaled based on your current population. The greater number of inhabitants you have, the greater the number of attackers you will have. Having a larger population also allows for different types of attackers to come.
Initially the main threat will be wolves. Wolves pose little threat, but will consume your workers if left unchecked. Beyond wolves, a civilization can be attacked by bandits. Bandits also have the threat of stealing resources. If left unchecked and in large numbers, they can quickly deplete secondary and tertiary resources. The only group worse than bandits are barbarians which simply attack in large numbers. Once a certain point has been reached, bandits and barbarian groups will also attack with siege engines in order to destroy fortifications. These siege engines can be captured though, and added to a civilization's own total.
The Trader arrives at random intervals and offers to trade large quantities of resources in exchange for gold. The amount is a randomized number between 1 and 20 times 5000 for primary resources, 500 for secondary resources, and 250 for tertiary resources. For each group of resources sold to the trader, one gold is received in exchange.