Hence, a world history study may involve cultures that actually had contact and influence on one another, or cultures that went through various stages of development with little or no outside influence. Since history is full of this kind of material, the number of possible world history treatments is very large. World history tends to be more superficial and general than local or national histories. This is not meant in a negative way, but in the sense of a comprehensive view of history. The old cliche of not seeing the forest for the trees applies here.
World history looks at the forest in that it searches for the overall, global meaning of history.
The major changes over the time the earth has existed, and particularly since the advent of humans, are emphasized and often displayed on time lines. In order to simplify this material they look for patterns of government or religion or other cultural and social institutions. They also stress connections between civilizations and how they influenced one another. There are many variations of cultural influence due to the different kinds of contacts that occurred, but the most common and most important is syncretism. As items and cultural developments diffuse from society to society, changes take place in any given civilization that fundamentally alter it.