Perhaps a map of the world with a timeline slider at the bottom. The map would need clickable bubbles which are larger or smaller relative to the significance of the event.

Zoom out for a smaller number of more significant global events. Zoom in and, like Google maps does with cities, show an increasing number of less significant events local to the zoomed in area.

For example, zoomed out in 1692, we see a slave revolt in Barbados, a large bubble for Europe's ongoing Nine-Years' War, and the Salem Witch Trials.

Zoom in on Salem and see little bubbles appearing with specific witch trials.

Now, to truly bring home your idea, add weighted dotted lines between events. The strength of the relationship between events would influence the weight and opacity of the dotted lines between events.