The revolution that led to the widespread use of agriculture (the Neolithic Revolution) was the most important factor in allowing civilization to begin. Agriculture is necessary in order for civilization to exist.
Before agriculture, all people were hunter-gatherers. This means that they got their food by hunting animals and by gathering things like fruits, roots, and nuts that grew wild. Almost all hunter-gatherers had to live nomadic lifestyles because there was not enough food in one place to allow them to be sedentary.
Agriculture allowed people to become sedentary and sedentary life is necessary for civilization. When people are nomadic, they cannot have dense populations. There are typically not enough food resources in the wild to feed dense populations. When people are nomadic, they cannot have much technology because they have to carry everything they have from place to place. When agriculture comes about, populations become denser. There is more food and so not everyone has to work at getting food. People can have the time that they need to create technology. Dense populations lead to the need for government. In short, agriculture leads to the dense, sedentary populations that are needed in order for civilization to exist.